refactor(backend): optimize database safety, validator performance, and scheduler concurrency

- Fix SQL injection risks in proxy_repo and task_repo
- Atomic acquire_pending with UPDATE ... RETURNING
- Reuse aiohttp ClientSession in ValidatorService
- Replace polling with asyncio.Event in SchedulerService
- Optimize ValidationQueue.drain with asyncio.Condition
- Concurrent plugin crawling with asyncio.gather
- Unify ProxyRaw model import path
- Fix test baseline and remove tracked __pycache__ files

app/api/lifespan.py

@@ -38,4 +38,5 @@ async def lifespan(app: FastAPI):
 
     # 关闭调度器
     await scheduler_service.stop()
+    await scheduler_service.validation_queue.validator.close()
     logger.info("API server shutdown")

app/api/routes/scheduler.py

@@ -49,7 +49,7 @@ async def stop_scheduler(scheduler: SchedulerService = Depends(get_scheduler_ser
 @router.post("/validate-now")
 async def validate_now(scheduler: SchedulerService = Depends(get_scheduler_service)):
     try:
-        scheduler.validate_all_now()
+        await scheduler.validate_all_now()
         return success_response("已开始全量验证", {"started": True})
     except Exception as e:
         logger.error(f"Validate now failed: {e}")