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/plugin_service.py

@@ -31,11 +31,20 @@ class PluginService:
             if "config" in state and isinstance(state["config"], dict):
                 plugin.update_config(state["config"])
 
-            stat = self._stats.get(plugin.name, {
-                "success_count": 0,
-                "failure_count": 0,
-                "last_run": None,
-            })
+            # 合并数据库统计与内存统计（内存优先）
+            db_stat = state.get("stats", {})
+            stat = {
+                "success_count": db_stat.get("success_count", 0),
+                "failure_count": db_stat.get("failure_count", 0),
+                "last_run": datetime.fromisoformat(db_stat["last_run"]) if db_stat.get("last_run") else None,
+            }
+            mem_stat = self._stats.get(plugin.name, {})
+            if mem_stat:
+                stat["success_count"] = mem_stat.get("success_count", stat["success_count"])
+                stat["failure_count"] = mem_stat.get("failure_count", stat["failure_count"])
+                if mem_stat.get("last_run"):
+                    stat["last_run"] = mem_stat["last_run"]
+
             result.append(PluginInfo(
                 id=plugin.name,
                 name=plugin.name,
@@ -105,11 +114,19 @@ class PluginService:
             self._record_stat(plugin_id, failure=1)
             logger.error(f"Plugin {plugin_id} crawl failed: {e}")
             return []
+        finally:
+            await self._save_stats(plugin_id)
 
     async def run_all_plugins(self) -> List[ProxyRaw]:
-        """执行所有启用插件的爬取"""
+        """执行所有启用插件的爬取，限制并发数以避免触发目标站反爬"""
         all_results: List[ProxyRaw] = []
-        tasks = [self.run_plugin(plugin.name) for plugin in registry.list_plugins() if plugin.enabled]
+        semaphore = asyncio.Semaphore(5)
+
+        async def _run_with_limit(plugin_name: str):
+            async with semaphore:
+                return await self.run_plugin(plugin_name)
+
+        tasks = [_run_with_limit(plugin.name) for plugin in registry.list_plugins() if plugin.enabled]
         results_list = await asyncio.gather(*tasks, return_exceptions=True)
         for results in results_list:
             if isinstance(results, Exception):
@@ -137,3 +154,14 @@ class PluginService:
         self._stats[plugin_id]["failure_count"] += failure
         if success or failure:
             self._stats[plugin_id]["last_run"] = datetime.now()
+
+    async def _save_stats(self, plugin_id: str):
+        """将内存中的统计持久化到数据库"""
+        stats = self._stats.get(plugin_id, {})
+        payload = {
+            "success_count": stats.get("success_count", 0),
+            "failure_count": stats.get("failure_count", 0),
+            "last_run": stats.get("last_run").isoformat() if stats.get("last_run") else None,
+        }
+        async with get_db() as db:
+            await self.plugin_settings_repo.set_stats(db, plugin_id, payload)