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

tests/conftest.py

@@ -1,7 +1,7 @@
 """pytest 配置文件和 fixtures"""
 import pytest
-import asyncio
-from typing import AsyncGenerator, Generator
+import pytest_asyncio
+from typing import AsyncGenerator
 from httpx import AsyncClient, ASGITransport
 
 from app.api import create_app
@@ -9,24 +9,17 @@ from app.core.db import init_db, get_db
 from app.repositories.proxy_repo import ProxyRepository
 
 
-@pytest.fixture(scope="session")
-def event_loop() -> Generator[asyncio.AbstractEventLoop, None, None]:
-    """创建事件循环"""
-    loop = asyncio.get_event_loop_policy().new_event_loop()
-    yield loop
-    loop.close()
-
-
-@pytest.fixture(scope="session")
+@pytest_asyncio.fixture(scope="function")
 async def app():
     """创建应用实例"""
     # 初始化测试数据库
     await init_db()
     app = create_app()
-    return app
+    async with app.router.lifespan_context(app):
+        yield app
 
 
-@pytest.fixture
+@pytest_asyncio.fixture
 async def client(app) -> AsyncGenerator[AsyncClient, None]:
     """创建异步 HTTP 客户端"""
     transport = ASGITransport(app=app)
@@ -34,20 +27,20 @@ async def client(app) -> AsyncGenerator[AsyncClient, None]:
         yield client
 
 
-@pytest.fixture
+@pytest_asyncio.fixture
 async def db():
     """获取数据库连接"""
     async with get_db() as db:
         yield db
 
 
-@pytest.fixture
+@pytest_asyncio.fixture
 async def proxy_repo():
     """获取代理仓库"""
     return ProxyRepository()
 
 
-@pytest.fixture
+@pytest_asyncio.fixture
 async def sample_proxy(db, proxy_repo):
     """创建一个测试代理"""
     await proxy_repo.insert_or_update(db, "192.168.1.1", 8080, "http", 50)