Add Web Dashboard with multi-device control and callback hooks

Features:
- Web Dashboard: FastAPI-based dashboard with Vue.js frontend
  - Multi-device support (ADB, HDC, iOS)
  - Real-time WebSocket updates for task progress
  - Device management with status tracking
  - Task queue with execution controls (start/stop/re-execute)
  - Detailed task information display (thinking, actions, completion messages)
  - Screenshot viewing per device
  - LAN deployment support with configurable CORS

- Callback Hooks: Interrupt and modify task execution
  - step_callback: Called after each step with StepResult
  - before_action_callback: Called before executing action
  - Support for task interruption and dynamic task switching
  - Example scripts demonstrating callback usage

- Configuration: Environment-based configuration
  - .env file support for all settings
  - .env.example template with documentation
  - Model API configuration (base URL, model name, API key)
  - Dashboard configuration (host, port, CORS, device type)
  - Phone agent configuration (delays, max steps, language)

Technical improvements:
- Fixed forward reference issue with StepResult
- Added package exports for callback types and configs
- Enhanced dependencies with FastAPI, WebSocket support
- Thread-safe task execution with device locking
- Async WebSocket broadcasting from sync thread pool

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

dashboard/models/task.py

@@ -0,0 +1,81 @@
+"""
+Task data models for the dashboard.
+"""
+
+from datetime import datetime
+from enum import Enum
+from typing import Any, Dict, Optional
+
+from pydantic import BaseModel, Field
+
+from phone_agent.model import ModelConfig
+
+
+class TaskStatus(str, Enum):
+    """Task execution status."""
+
+    PENDING = "pending"
+    RUNNING = "running"
+    COMPLETED = "completed"
+    FAILED = "failed"
+    STOPPED = "stopped"
+
+
+class TaskCreateRequest(BaseModel):
+    """Request to create a new task."""
+
+    device_id: str = Field(..., description="Target device ID")
+    task: str = Field(..., description="Task description")
+    max_steps: int = Field(100, description="Maximum execution steps")
+    lang: str = Field("cn", description="Language (cn or en)")
+
+    # Model config - use dict to avoid validation issues with ModelConfig
+    base_url: str = Field(
+        default="http://localhost:8000/v1", description="Model API base URL"
+    )
+    model_name: str = Field(default="autoglm-phone-9b", description="Model name")
+    api_key: str = Field(default="EMPTY", description="API key")
+    max_tokens: int = Field(default=3000, description="Max tokens per response")
+    temperature: float = Field(default=0.0, description="Sampling temperature")
+    top_p: float = Field(default=0.85, description="Top-p sampling parameter")
+    frequency_penalty: float = Field(default=0.2, description="Frequency penalty")
+
+
+class TaskSchema(BaseModel):
+    """Task schema for API responses."""
+
+    task_id: str = Field(..., description="Unique task identifier")
+    device_id: str = Field(..., description="Target device ID")
+    task: str = Field(..., description="Task description")
+    status: TaskStatus = Field(..., description="Task status")
+    current_step: int = Field(0, description="Current step number")
+    max_steps: int = Field(100, description="Maximum steps")
+    current_action: Optional[Dict[str, Any]] = Field(None, description="Current action")
+    thinking: Optional[str] = Field(None, description="Current thinking/reasoning")
+    started_at: datetime = Field(..., description="Task start time")
+    updated_at: datetime = Field(..., description="Last update time")
+    finished_at: Optional[datetime] = Field(None, description="Task completion time")
+    error: Optional[str] = Field(None, description="Error message if failed")
+    completion_message: Optional[str] = Field(
+        None, description="Task completion message with details"
+    )
+
+    class Config:
+        json_schema_extra = {
+            "example": {
+                "task_id": "task_123456",
+                "device_id": "emulator-5554",
+                "task": "Open WeChat",
+                "status": "running",
+                "current_step": 3,
+                "max_steps": 100,
+                "current_action": {"action": "Tap", "element": "WeChat icon"},
+                "thinking": "Looking for WeChat icon on home screen",
+                "started_at": "2024-01-09T10:00:00",
+                "updated_at": "2024-01-09T10:00:15",
+            }
+        }
+
+
+# For backward compatibility
+TaskRequest = TaskCreateRequest