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/fate0.py

@@ -13,27 +13,34 @@ class Fate0Plugin(BaseHTTPPlugin):
 
     def __init__(self):
         super().__init__()
-        self.urls = ["https://raw.githubusercontent.com/fate0/proxylist/master/proxy.list"]
+        self.urls = [
+            "https://raw.githubusercontent.com/fate0/proxylist/master/proxy.list",
+            "https://cdn.jsdelivr.net/gh/fate0/proxylist@master/proxy.list",
+        ]
 
     async def crawl(self) -> List[ProxyRaw]:
         results = []
+        # 顺序 fetch，带 fallback
         for url in self.urls:
             html = await self.fetch(url, timeout=30)
-            if not html:
+            if html:
+                break
+        if not html:
+            logger.warning(f"{self.display_name} 所有源均不可用")
+            return results
+        for line in html.split("\n"):
+            line = line.strip()
+            if not line:
+                continue
+            try:
+                data = json.loads(line)
+                ip = data.get("host")
+                port = data.get("port")
+                protocol = data.get("type", "http")
+                if ip and port:
+                    results.append(ProxyRaw(ip, int(port), protocol))
+            except Exception:
                 continue
-            for line in html.split("\n"):
-                line = line.strip()
-                if not line:
-                    continue
-                try:
-                    data = json.loads(line)
-                    ip = data.get("host")
-                    port = data.get("port")
-                    protocol = data.get("type", "http")
-                    if ip and port:
-                        results.append(ProxyRaw(ip, int(port), protocol))
-                except Exception:
-                    continue
         if results:
             logger.info(f"{self.display_name} 解析完成，获取 {len(results)} 个潜在代理")
         return results