feat: initial XCClaw基础架构

- 基于 FastAPI 的 Web API 服务
- OpenCode API 客户端封装
- 会话管理器（同步/异步任务执行）
- APScheduler 定时任务调度
- 完整的 REST API 端点

app/api/__init__.py

@@ -0,0 +1 @@
+from app.api.routes import router

app/api/routes.py

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+from fastapi import APIRouter, HTTPException
+from app.models.session import CreateSessionRequest, SessionType
+from app.services.session_manager import session_manager
+from app.services.scheduler import scheduler_service, ScheduleTask
+from app.services.opencode_client import opencode_client
+
+
+router = APIRouter(prefix="/api/xcclaw", tags=["xcclaw"])
+
+
+@router.get("/health")
+async def health_check():
+    try:
+        opencode_status = await opencode_client.health_check()
+        return {"status": "ok", "opencode": opencode_status}
+    except Exception as e:
+        return {"status": "error", "message": str(e)}
+
+
+@router.post("/task")
+async def create_task(request: CreateSessionRequest):
+    task = await session_manager.create_task(request)
+    return task
+
+
+@router.post("/task/{task_id}/execute")
+async def execute_task(task_id: str):
+    result = await session_manager.execute_task(task_id)
+    return result
+
+
+@router.post("/task/{task_id}/execute_async")
+async def execute_task_async(task_id: str):
+    await session_manager.execute_task_async(task_id)
+    return {"status": "started", "task_id": task_id}
+
+
+@router.post("/task/{task_id}/abort")
+async def abort_task(task_id: str):
+    result = await session_manager.abort_task(task_id)
+    return {"aborted": result}
+
+
+@router.get("/task/{task_id}")
+async def get_task(task_id: str):
+    task = await session_manager.get_task(task_id)
+    if not task:
+        raise HTTPException(status_code=404, detail="Task not found")
+    return task
+
+
+@router.get("/task")
+async def list_tasks():
+    return await session_manager.list_tasks()
+
+
+@router.post("/schedule")
+async def create_schedule(task: ScheduleTask):
+    return await scheduler_service.add_schedule(task)
+
+
+@router.get("/schedule")
+async def list_schedules():
+    return await scheduler_service.list_schedules()
+
+
+@router.delete("/schedule/{schedule_id}")
+async def delete_schedule(schedule_id: str):
+    result = await scheduler_service.remove_schedule(schedule_id)
+    if not result:
+        raise HTTPException(status_code=404, detail="Schedule not found")
+    return {"deleted": True}