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/plugins/ip3366.py

@@ -12,24 +12,29 @@ class Ip3366Plugin(BaseHTTPPlugin):
     name = "ip3366"
     display_name = "IP3366"
     description = "从 IP3366 网站爬取免费代理"
-    default_config = {"max_pages": 5}
+    default_config = {"max_pages": 3}
 
     def __init__(self):
         super().__init__()
         self._update_urls()
 
     def _update_urls(self):
-        max_pages = self.config.get("max_pages", 5)
+        max_pages = self.config.get("max_pages", 3)
         self.urls = [
             f"http://www.ip3366.net/free/?stype=1&page={i}" for i in range(1, max_pages + 1)
         ] + [
             f"http://www.ip3366.net/free/?stype=2&page={i}" for i in range(1, max_pages + 1)
         ]
 
+    def get_headers(self) -> dict:
+        headers = super().get_headers()
+        headers["Referer"] = "http://www.ip3366.net/free/"
+        return headers
+
     async def crawl(self) -> List[ProxyRaw]:
         results = []
-        for url in self.urls:
-            html = await self.fetch(url, timeout=15)
+        htmls = await self.fetch_all(self.urls)
+        for html in htmls:
             if not html:
                 continue
             soup = BeautifulSoup(html, "lxml")