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/kuaidaili.py

@@ -1,4 +1,6 @@
 import re
+import asyncio
+import random
 from typing import List
 from bs4 import BeautifulSoup
 from app.core.plugin_system import ProxyRaw
@@ -16,22 +18,39 @@ class KuaiDaiLiPlugin(BaseHTTPPlugin):
 
     def __init__(self):
         super().__init__()
+        # 减少页数，降低被反爬概率，确保至少能拿到数据
         self.urls = [
-            f"https://www.kuaidaili.com/free/inha/{i}/" for i in range(1, 11)
-        ] + [
-            f"https://www.kuaidaili.com/free/intr/{i}/" for i in range(1, 11)
+            "https://www.kuaidaili.com/free/inha/1/",
+            "https://www.kuaidaili.com/free/intr/1/",
         ]
 
+    def get_headers(self) -> dict:
+        headers = super().get_headers()
+        headers["Referer"] = "https://www.kuaidaili.com/free/inha/"
+        headers["Accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8"
+        headers["Accept-Encoding"] = "gzip, deflate, br"
+        headers["Accept-Language"] = "zh-CN,zh;q=0.9,en;q=0.8"
+        headers["Sec-Fetch-Dest"] = "document"
+        headers["Sec-Fetch-Mode"] = "navigate"
+        headers["Sec-Fetch-Site"] = "same-origin"
+        headers["Upgrade-Insecure-Requests"] = "1"
+        return headers
+
     async def crawl(self) -> List[ProxyRaw]:
         results = []
+        # 先访问首页预热会话，获取 cookie，降低被反爬概率
+        await self.fetch("https://www.kuaidaili.com/", timeout=10)
+        await asyncio.sleep(random.uniform(2, 4))
+
+        # 顺序请求免费代理页面
         for url in self.urls:
-            html = await self.fetch(url, timeout=15)
+            html = await self.fetch(url, timeout=10)
             if not html:
                 continue
             soup = BeautifulSoup(html, "lxml")
             table = soup.find("table")
             if not table:
-                logger.warning(f"{self.display_name} 未能找到表格，可能是触发了反爬")
+                logger.warning(f"{self.display_name} 未能找到表格，可能是触发了反爬: {url}")
                 continue
 
             for row in table.find_all("tr"):
@@ -44,6 +63,7 @@ class KuaiDaiLiPlugin(BaseHTTPPlugin):
                         protocol = "http"
                     if re.match(r"^\d+\.\d+\.\d+\.\d+$", ip) and port.isdigit():
                         results.append(ProxyRaw(ip, int(port), protocol))
+            await asyncio.sleep(random.uniform(5, 8))
 
         if results:
             logger.info(f"{self.display_name} 解析完成，获取 {len(results)} 个潜在代理")