fix: 修复裁剪手势状态丢失 + 合并重复预览代码

- 为 MagnificationGesture/DragGesture 添加 .onEnded 处理器，
  新增 lastCropOffset/lastCropScale 累积变量，修复抬手后
  缩放/偏移从初始值重新开始的问题
- 提取 cropPreview(height:dynamicHeight:) 共享方法和
  cropGesture 计算属性，消除 iPhone/iPad 约 60 行重复代码
- resetCropState() 同步重置累积变量

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

to-live-photo/to-live-photo/Views/EditorView.swift

@@ -31,6 +31,8 @@ struct EditorView: View {
     // 裁剪相关（归一化坐标）
     @State private var cropOffset: CGSize = .zero   // 拖拽偏移
     @State private var cropScale: CGFloat = 1.0     // 缩放比例
+    @State private var lastCropOffset: CGSize = .zero  // 累积偏移
+    @State private var lastCropScale: CGFloat = 1.0    // 累积缩放
 
     // 兼容模式
     @State private var compatibilityMode: Bool = false
@@ -72,7 +74,7 @@ struct EditorView: View {
     private var iPhoneLayout: some View {
         ScrollView {
             VStack(spacing: 20) {
-                cropPreviewSection
+                cropPreview(height: 360)
 
                 if let diagnosis = videoDiagnosis, !diagnosis.suggestions.isEmpty {
                     diagnosisSection(diagnosis: diagnosis)
@@ -97,7 +99,7 @@ struct EditorView: View {
         HStack(alignment: .top, spacing: 24) {
             // 左侧：视频预览
             VStack(spacing: 16) {
-                iPadCropPreviewSection
+                cropPreview(height: 500, dynamicHeight: true)
 
                 if let diagnosis = videoDiagnosis, !diagnosis.suggestions.isEmpty {
                     diagnosisSection(diagnosis: diagnosis)
@@ -124,80 +126,50 @@ struct EditorView: View {
         .padding(DesignTokens.Spacing.xxl)
     }
 
-    // MARK: - iPad 裁剪预览（更大尺寸）
+    // MARK: - 裁剪手势
-    @ViewBuilder
+    private var cropGesture: some Gesture {
-    private var iPadCropPreviewSection: some View {
+        SimultaneousGesture(
-        GeometryReader { geometry in
+            MagnificationGesture()
-            let containerWidth = geometry.size.width
+                .onChanged { value in
-            let containerHeight = min(500, geometry.size.width * 1.2)
+                    cropScale = max(1.0, min(3.0, lastCropScale * value))
-
-            ZStack {
-                if let player {
-                    VideoPlayer(player: player)
-                        .aspectRatio(videoNaturalSize, contentMode: .fit)
-                        .scaleEffect(cropScale)
-                        .offset(cropOffset)
-                        .gesture(
-                            SimultaneousGesture(
-                                MagnificationGesture()
-                                    .onChanged { value in
-                                        cropScale = max(1.0, min(3.0, value))
-                                    },
-                                DragGesture()
-                                    .onChanged { value in
-                                        cropOffset = value.translation
-                                    }
-                            )
-                        )
-                } else {
-                    ProgressView()
                 }
-
+                .onEnded { value in
-                if selectedAspectRatio != .original {
+                    lastCropScale = max(1.0, min(3.0, lastCropScale * value))
-                    CropOverlay(
+                },
-                        aspectRatio: selectedAspectRatio,
+            DragGesture()
-                        containerSize: CGSize(width: containerWidth, height: containerHeight)
+                .onChanged { value in
+                    cropOffset = CGSize(
+                        width: lastCropOffset.width + value.translation.width,
+                        height: lastCropOffset.height + value.translation.height
                     )
                 }
-            }
+                .onEnded { value in
-            .frame(width: containerWidth, height: containerHeight)
+                    lastCropOffset = CGSize(
-            .clipShape(RoundedRectangle(cornerRadius: 16))
+                        width: lastCropOffset.width + value.translation.width,
-            .background(Color.black.clipShape(RoundedRectangle(cornerRadius: 16)))
+                        height: lastCropOffset.height + value.translation.height
-        }
+                    )
-        .frame(height: 500)
+                }
+        )
     }
 
-    // MARK: - 裁剪预览
+    // MARK: - 裁剪预览（共享）
     @ViewBuilder
-    private var cropPreviewSection: some View {
+    private func cropPreview(height: CGFloat, dynamicHeight: Bool = false) -> some View {
         GeometryReader { geometry in
             let containerWidth = geometry.size.width
-            let containerHeight: CGFloat = 360
+            let containerHeight = dynamicHeight ? min(height, geometry.size.width * 1.2) : height
 
             ZStack {
-                // 视频预览（全画幅）
                 if let player {
                     VideoPlayer(player: player)
                         .aspectRatio(videoNaturalSize, contentMode: .fit)
                         .scaleEffect(cropScale)
                         .offset(cropOffset)
-                        .gesture(
+                        .gesture(cropGesture)
-                            SimultaneousGesture(
-                                MagnificationGesture()
-                                    .onChanged { value in
-                                        cropScale = max(1.0, min(3.0, value))
-                                    },
-                                DragGesture()
-                                    .onChanged { value in
-                                        cropOffset = value.translation
-                                    }
-                            )
-                        )
                 } else {
                     ProgressView()
                 }
 
-                // 裁剪框叠加层
                 if selectedAspectRatio != .original {
                     CropOverlay(
                         aspectRatio: selectedAspectRatio,
@@ -209,7 +181,7 @@ struct EditorView: View {
             .clipShape(RoundedRectangle(cornerRadius: 16))
             .background(Color.black.clipShape(RoundedRectangle(cornerRadius: 16)))
         }
-        .frame(height: 360)
+        .frame(height: height)
     }
 
     // MARK: - 比例模板选择
@@ -710,6 +682,8 @@ struct EditorView: View {
     private func resetCropState() {
         cropOffset = .zero
         cropScale = 1.0
+        lastCropOffset = .zero
+        lastCropScale = 1.0
     }
 
     private func calculateCropRect() -> CropRect {