fix: 修复爬虫网络层、验证队列卡死及 API 500 错误

- 修复 BaseHTTPPlugin 连接池、并发控制、异常日志、超时策略
- 修复/增强 8 个爬虫插件的稳定性和 fallback 机制
- 清理 validation_tasks 表 4 万+ pending 任务，避免队列卡死
- 修复 app/api/main.py 缺失全局 app 实例导致的 500 错误
- 提升前端 Axios 超时到 120 秒，避免请求断开
- 修复插件统计持久化和调度器生命周期问题

app/services/scheduler_service.py

@@ -22,6 +22,7 @@ class SchedulerService:
         self.running = False
         self._stop_event = asyncio.Event()
         self._task: asyncio.Task | None = None
+        self._validate_task: asyncio.Task | None = None
 
     async def start(self):
         if self.running:
@@ -48,7 +49,9 @@ class SchedulerService:
 
     async def validate_all_now(self):
         """立即执行一次全量验证（后台运行，不阻塞）"""
-        asyncio.create_task(self._do_validate_all())
+        if self._validate_task and not self._validate_task.done():
+            return
+        self._validate_task = asyncio.create_task(self._do_validate_all())
 
     async def _run_loop(self):
         """定时循环"""
@@ -65,27 +68,30 @@ class SchedulerService:
 
     async def _do_validate_all(self):
         """验证数据库中所有存量代理"""
-        logger.info("Starting scheduled validation for all proxies")
-        async with get_db() as db:
-            proxies = await self.proxy_repo.list_all(db)
-        if not proxies:
-            logger.info("No proxies to validate")
-            return
+        try:
+            logger.info("Starting scheduled validation for all proxies")
+            async with get_db() as db:
+                proxies = await self.proxy_repo.list_all(db)
+            if not proxies:
+                logger.info("No proxies to validate")
+                return
 
-        logger.info(f"Validating {len(proxies)} proxies from database")
-        from app.models.domain import ProxyRaw
+            logger.info(f"Validating {len(proxies)} proxies from database")
+            from app.models.domain import ProxyRaw
 
-        # 批量提交到验证队列
-        batch_size = 100
-        for i in range(0, len(proxies), batch_size):
-            if not self.running:
-                break
-            batch = proxies[i : i + batch_size]
-            await self.validation_queue.submit([
-                ProxyRaw(p.ip, p.port, p.protocol) for p in batch
-            ])
-            # 等待当前批次处理完
-            await self.validation_queue.drain()
-            logger.info(f"Validated batch {i//batch_size + 1}/{(len(proxies)-1)//batch_size + 1}")
+            # 批量提交到验证队列
+            batch_size = 100
+            for i in range(0, len(proxies), batch_size):
+                if not self.running:
+                    break
+                batch = proxies[i : i + batch_size]
+                await self.validation_queue.submit([
+                    ProxyRaw(p.ip, p.port, p.protocol) for p in batch
+                ])
+                # 等待当前批次处理完
+                await self.validation_queue.drain()
+                logger.info(f"Validated batch {i//batch_size + 1}/{(len(proxies)-1)//batch_size + 1}")
 
-        logger.info("Scheduled validation completed")
+            logger.info("Scheduled validation completed")
+        except Exception as e:
+            logger.error(f"Scheduled validation error: {e}")