feat: 添加桌面版应用和心跳监控

新增功能：
- src/desktop.py: PyQt6 桌面应用，支持 Droidcam 摄像头
  - 实时视频预览 + 绿色扫描框叠加
  - 空格键快速拍照识别
  - 批量记录管理和 Excel 导出
- heartbeat.py: 服务心跳监控，自动重启 Streamlit
- requirements-desktop.txt: 桌面版专用依赖

Web 版优化：
- src/app.py: 自定义摄像头组件，扫描框叠加到视频流

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/desktop.py

@@ -0,0 +1,354 @@
+#!/usr/bin/env python3
+"""
+信封信息提取系统 - 桌面版
+使用 Droidcam 将手机作为摄像头，实时预览并识别信封信息
+"""
+import os
+import sys
+import cv2
+import tempfile
+import pandas as pd
+from datetime import datetime
+from pathlib import Path
+
+from PyQt6.QtWidgets import (
+    QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout,
+    QPushButton, QLabel, QTableWidget, QTableWidgetItem, QComboBox,
+    QFileDialog, QMessageBox, QGroupBox, QSplitter, QHeaderView,
+    QStatusBar, QProgressBar
+)
+from PyQt6.QtCore import Qt, QTimer, QThread, pyqtSignal
+from PyQt6.QtGui import QImage, QPixmap, QFont, QAction
+
+from paddleocr import PaddleOCR
+from processor import extract_info
+
+os.environ["PADDLE_PDX_DISABLE_MODEL_SOURCE_CHECK"] = "True"
+
+
+class OCRWorker(QThread):
+    """OCR 识别线程"""
+    finished = pyqtSignal(dict, list)
+    error = pyqtSignal(str)
+
+    def __init__(self, ocr, image_path):
+        super().__init__()
+        self.ocr = ocr
+        self.image_path = image_path
+
+    def run(self):
+        try:
+            result = self.ocr.ocr(self.image_path, cls=False)
+            ocr_texts = []
+            if result and result[0]:
+                for line in result[0]:
+                    if line and len(line) >= 2:
+                        ocr_texts.append(line[1][0])
+            record = extract_info(ocr_texts)
+            self.finished.emit(record, ocr_texts)
+        except Exception as e:
+            self.error.emit(str(e))
+
+
+class MainWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+        self.setWindowTitle("📮 信封信息提取系统")
+        self.setMinimumSize(1200, 700)
+
+        # 初始化 OCR
+        self.statusBar().showMessage("正在加载 OCR 模型...")
+        QApplication.processEvents()
+        self.ocr = PaddleOCR(use_textline_orientation=True, lang="ch", show_log=False)
+        self.statusBar().showMessage("OCR 模型加载完成")
+
+        # 摄像头
+        self.cap = None
+        self.timer = QTimer()
+        self.timer.timeout.connect(self.update_frame)
+
+        # 数据
+        self.records = []
+
+        self.init_ui()
+        self.load_cameras()
+
+    def init_ui(self):
+        central = QWidget()
+        self.setCentralWidget(central)
+        layout = QHBoxLayout(central)
+
+        # 左侧：摄像头预览
+        left_panel = QGroupBox("📷 摄像头预览")
+        left_layout = QVBoxLayout(left_panel)
+
+        # 摄像头选择
+        cam_layout = QHBoxLayout()
+        cam_layout.addWidget(QLabel("摄像头:"))
+        self.cam_combo = QComboBox()
+        self.cam_combo.setMinimumWidth(200)
+        cam_layout.addWidget(self.cam_combo)
+        self.btn_refresh = QPushButton("🔄 刷新")
+        self.btn_refresh.clicked.connect(self.load_cameras)
+        cam_layout.addWidget(self.btn_refresh)
+        self.btn_connect = QPushButton("▶ 连接")
+        self.btn_connect.clicked.connect(self.toggle_camera)
+        cam_layout.addWidget(self.btn_connect)
+        cam_layout.addStretch()
+        left_layout.addLayout(cam_layout)
+
+        # 视频画面
+        self.video_label = QLabel()
+        self.video_label.setMinimumSize(640, 480)
+        self.video_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        self.video_label.setStyleSheet("background-color: #1a1a1a; border: 2px solid #333; border-radius: 8px;")
+        self.video_label.setText("点击「连接」启动摄像头\n\n支持 Droidcam / Iriun 等虚拟摄像头")
+        left_layout.addWidget(self.video_label)
+
+        # 拍照按钮
+        self.btn_capture = QPushButton("📸 拍照识别 (空格键)")
+        self.btn_capture.setMinimumHeight(50)
+        self.btn_capture.setFont(QFont("", 14))
+        self.btn_capture.setStyleSheet("background-color: #ff4b4b; color: white; border-radius: 8px;")
+        self.btn_capture.clicked.connect(self.capture_and_recognize)
+        self.btn_capture.setEnabled(False)
+        left_layout.addWidget(self.btn_capture)
+
+        # 右侧：结果列表
+        right_panel = QGroupBox(f"📋 已识别记录 (0)")
+        self.right_panel = right_panel
+        right_layout = QVBoxLayout(right_panel)
+
+        # 表格
+        self.table = QTableWidget()
+        self.table.setColumnCount(5)
+        self.table.setHorizontalHeaderLabels(["编号", "邮编", "地址", "联系人", "电话"])
+        self.table.horizontalHeader().setSectionResizeMode(2, QHeaderView.ResizeMode.Stretch)
+        self.table.setSelectionBehavior(QTableWidget.SelectionBehavior.SelectRows)
+        right_layout.addWidget(self.table)
+
+        # 操作按钮
+        btn_layout = QHBoxLayout()
+        self.btn_delete = QPushButton("🗑 删除选中")
+        self.btn_delete.clicked.connect(self.delete_selected)
+        btn_layout.addWidget(self.btn_delete)
+
+        self.btn_clear = QPushButton("🧹 清空全部")
+        self.btn_clear.clicked.connect(self.clear_all)
+        btn_layout.addWidget(self.btn_clear)
+
+        self.btn_export = QPushButton("📥 导出 Excel")
+        self.btn_export.setStyleSheet("background-color: #4CAF50; color: white;")
+        self.btn_export.clicked.connect(self.export_excel)
+        btn_layout.addWidget(self.btn_export)
+
+        right_layout.addLayout(btn_layout)
+
+        # 分割器
+        splitter = QSplitter(Qt.Orientation.Horizontal)
+        splitter.addWidget(left_panel)
+        splitter.addWidget(right_panel)
+        splitter.setSizes([600, 500])
+        layout.addWidget(splitter)
+
+        # 快捷键
+        self.shortcut_capture = QAction(self)
+        self.shortcut_capture.setShortcut("Space")
+        self.shortcut_capture.triggered.connect(self.capture_and_recognize)
+        self.addAction(self.shortcut_capture)
+
+    def load_cameras(self):
+        """扫描可用摄像头"""
+        self.cam_combo.clear()
+        for i in range(10):
+            cap = cv2.VideoCapture(i)
+            if cap.isOpened():
+                ret, _ = cap.read()
+                if ret:
+                    self.cam_combo.addItem(f"摄像头 {i}", i)
+                cap.release()
+
+        if self.cam_combo.count() == 0:
+            self.cam_combo.addItem("未检测到摄像头", -1)
+            self.statusBar().showMessage("未检测到摄像头，请连接 Droidcam")
+        else:
+            self.statusBar().showMessage(f"检测到 {self.cam_combo.count()} 个摄像头")
+
+    def toggle_camera(self):
+        """连接/断开摄像头"""
+        if self.cap is None:
+            cam_id = self.cam_combo.currentData()
+            if cam_id is None or cam_id < 0:
+                QMessageBox.warning(self, "错误", "请先选择有效的摄像头")
+                return
+
+            self.cap = cv2.VideoCapture(cam_id)
+            self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
+            self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)
+
+            if self.cap.isOpened():
+                self.timer.start(30)  # ~33 FPS
+                self.btn_connect.setText("⏹ 断开")
+                self.btn_capture.setEnabled(True)
+                self.cam_combo.setEnabled(False)
+                self.statusBar().showMessage("摄像头已连接")
+            else:
+                self.cap = None
+                QMessageBox.warning(self, "错误", "无法打开摄像头")
+        else:
+            self.timer.stop()
+            self.cap.release()
+            self.cap = None
+            self.btn_connect.setText("▶ 连接")
+            self.btn_capture.setEnabled(False)
+            self.cam_combo.setEnabled(True)
+            self.video_label.setText("摄像头已断开")
+            self.statusBar().showMessage("摄像头已断开")
+
+    def update_frame(self):
+        """更新视频帧"""
+        if self.cap is None:
+            return
+
+        ret, frame = self.cap.read()
+        if ret:
+            # 绘制扫描框
+            h, w = frame.shape[:2]
+            # 框的位置：上方 70%，编号在下方
+            x1, y1 = int(w * 0.06), int(h * 0.08)
+            x2, y2 = int(w * 0.94), int(h * 0.78)
+
+            # 绘制绿色边框
+            cv2.rectangle(frame, (x1, y1), (x2, y2), (0, 255, 0), 2)
+
+            # 四角加粗
+            corner_len = 25
+            cv2.line(frame, (x1, y1), (x1 + corner_len, y1), (0, 255, 0), 4)
+            cv2.line(frame, (x1, y1), (x1, y1 + corner_len), (0, 255, 0), 4)
+            cv2.line(frame, (x2, y1), (x2 - corner_len, y1), (0, 255, 0), 4)
+            cv2.line(frame, (x2, y1), (x2, y1 + corner_len), (0, 255, 0), 4)
+            cv2.line(frame, (x1, y2), (x1 + corner_len, y2), (0, 255, 0), 4)
+            cv2.line(frame, (x1, y2), (x1, y2 - corner_len), (0, 255, 0), 4)
+            cv2.line(frame, (x2, y2), (x2 - corner_len, y2), (0, 255, 0), 4)
+            cv2.line(frame, (x2, y2), (x2, y2 - corner_len), (0, 255, 0), 4)
+
+            # 提示文字
+            cv2.putText(frame, "You Bian", (x1 + 10, y1 + 25), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)
+            cv2.putText(frame, "Di Zhi", (x1 + 10, y1 + int((y2-y1)*0.4)), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)
+            cv2.putText(frame, "Lian Xi Ren", (x1 + 10, y2 - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)
+            cv2.putText(frame, "Dian Hua", (x2 - 80, y2 - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)
+
+            # 编号提示
+            cv2.putText(frame, "^ Bian Hao ^", (int(w*0.4), int(h*0.88)), cv2.FONT_HERSHEY_SIMPLEX, 0.6, (0, 255, 0), 2)
+
+            # 转换为 Qt 图像
+            rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
+            h, w, ch = rgb.shape
+            qimg = QImage(rgb.data, w, h, ch * w, QImage.Format.Format_RGB888)
+            scaled = qimg.scaled(self.video_label.size(), Qt.AspectRatioMode.KeepAspectRatio, Qt.TransformationMode.SmoothTransformation)
+            self.video_label.setPixmap(QPixmap.fromImage(scaled))
+
+    def capture_and_recognize(self):
+        """拍照并识别"""
+        if self.cap is None:
+            return
+
+        ret, frame = self.cap.read()
+        if not ret:
+            self.statusBar().showMessage("拍照失败")
+            return
+
+        # 保存临时文件
+        tmp_path = tempfile.mktemp(suffix=".jpg")
+        cv2.imwrite(tmp_path, frame)
+
+        self.statusBar().showMessage("正在识别...")
+        self.btn_capture.setEnabled(False)
+
+        # 启动 OCR 线程
+        self.worker = OCRWorker(self.ocr, tmp_path)
+        self.worker.finished.connect(lambda r, t: self.on_ocr_finished(r, t, tmp_path))
+        self.worker.error.connect(lambda e: self.on_ocr_error(e, tmp_path))
+        self.worker.start()
+
+    def on_ocr_finished(self, record, texts, tmp_path):
+        """OCR 完成"""
+        os.unlink(tmp_path)
+        self.btn_capture.setEnabled(True)
+
+        # 添加到记录
+        self.records.append(record)
+        self.update_table()
+
+        self.statusBar().showMessage(f"识别完成: {record.get('联系人/单位名', '未知')}")
+
+    def on_ocr_error(self, error, tmp_path):
+        """OCR 错误"""
+        os.unlink(tmp_path)
+        self.btn_capture.setEnabled(True)
+        self.statusBar().showMessage(f"识别失败: {error}")
+
+    def update_table(self):
+        """更新表格"""
+        self.table.setRowCount(len(self.records))
+        for i, r in enumerate(self.records):
+            self.table.setItem(i, 0, QTableWidgetItem(r.get("编号", "")))
+            self.table.setItem(i, 1, QTableWidgetItem(r.get("邮编", "")))
+            self.table.setItem(i, 2, QTableWidgetItem(r.get("地址", "")))
+            self.table.setItem(i, 3, QTableWidgetItem(r.get("联系人/单位名", "")))
+            self.table.setItem(i, 4, QTableWidgetItem(r.get("电话", "")))
+
+        self.right_panel.setTitle(f"📋 已识别记录 ({len(self.records)})")
+
+    def delete_selected(self):
+        """删除选中行"""
+        rows = set(item.row() for item in self.table.selectedItems())
+        for row in sorted(rows, reverse=True):
+            del self.records[row]
+        self.update_table()
+
+    def clear_all(self):
+        """清空全部"""
+        if self.records:
+            reply = QMessageBox.question(self, "确认", f"确定清空全部 {len(self.records)} 条记录？")
+            if reply == QMessageBox.StandardButton.Yes:
+                self.records.clear()
+                self.update_table()
+
+    def export_excel(self):
+        """导出 Excel"""
+        if not self.records:
+            QMessageBox.warning(self, "提示", "没有可导出的记录")
+            return
+
+        default_name = f"信封提取_{datetime.now():%Y%m%d_%H%M%S}.xlsx"
+        path, _ = QFileDialog.getSaveFileName(self, "保存 Excel", default_name, "Excel Files (*.xlsx)")
+
+        if path:
+            df = pd.DataFrame(self.records)
+            cols = ["编号", "邮编", "地址", "联系人/单位名", "电话"]
+            df = df.reindex(columns=cols)
+            df.to_excel(path, index=False)
+            self.statusBar().showMessage(f"已导出: {path}")
+            QMessageBox.information(self, "成功", f"已导出 {len(self.records)} 条记录到:\n{path}")
+
+    def closeEvent(self, event):
+        """关闭窗口"""
+        if self.cap:
+            self.timer.stop()
+            self.cap.release()
+        event.accept()
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+
+    window = MainWindow()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()