feat: Implement scheduling functionality for playlist synchronization

- Added a new scheduler module using APScheduler to manage scheduled sync jobs.
- Introduced cron expression validation and job scheduling based on user-defined settings.
- Enhanced frontend to support schedule settings, including cron, daily, and weekly modes.
- Updated API service to handle fetching and saving schedule settings.
- Modified StrategySelector component to include schedule management UI.
- Added new types for schedule settings and modes in the frontend.
- Updated requirements to include APScheduler for scheduling capabilities.

app/main.py

@@ -14,9 +14,14 @@ from app.utils.local_playlist import load_local_playlist, scan_local_playlists
 from app.utils.logger import logger
 from app.utils.playlist_merge import SyncMode, TEST_PLAYLIST_DIR, sync_all_playlists
 from app.utils.plex_client import plex_client
+from app.utils.scheduler import start_scheduler, update_scheduler_job, get_next_run_time, validate_cron_expression
 
 app = FastAPI()
 
+@app.on_event("startup")
+async def startup_event():
+    start_scheduler()
+
 app.add_middleware(
     CORSMiddleware,
     allow_origins=["*"],
@@ -107,6 +112,50 @@ class ConnectRequest(BaseModel):
     library_name: str | None = None
 
 
+class ScheduleSettings(BaseModel):
+    mode: str
+    cronExpression: str
+    dailyTime: str
+    weeklyDays: list[int]
+    weeklyTime: str
+    autoWatch: bool
+
+
+@app.get("/api/schedule")
+async def get_schedule():
+    next_run = get_next_run_time()
+    next_run_str = next_run.strftime("%Y-%m-%d %H:%M:%S") if next_run else None
+    
+    return {
+        "mode": server_config.schedule_mode,
+        "cronExpression": server_config.schedule_cron,
+        "dailyTime": server_config.schedule_daily_time,
+        "weeklyDays": server_config.schedule_weekly_days,
+        "weeklyTime": server_config.schedule_weekly_time,
+        "autoWatch": server_config.schedule_auto_watch,
+        "nextRun": next_run_str
+    }
+
+
+@app.put("/api/schedule")
+async def save_schedule(settings: ScheduleSettings):
+    # Validate Cron if mode is CRON
+    if settings.mode == "CRON" and settings.cronExpression.strip():
+        if not validate_cron_expression(settings.cronExpression):
+            raise HTTPException(status_code=400, detail="Invalid Cron expression format")
+
+    server_config.set_schedule(
+        mode=settings.mode,
+        cron=settings.cronExpression,
+        daily_time=settings.dailyTime,
+        weekly_days=settings.weeklyDays,
+        weekly_time=settings.weeklyTime,
+        auto_watch=settings.autoWatch
+    )
+    update_scheduler_job()
+    return {"status": "success", "message": "Schedule updated"}
+
+
 class ConnectResponse(BaseModel):
     token: str
     serverInfo: dict