fix: 修复主程序卡死与下载器集成，新增真实数据测试

- LookingWebMain: 强制 IPv4 避免 IPv6 不可达挂起；requests 加超时防卡死
- get_seed_from_element_detail: 修复限流页崩溃与 favicon 误作来源 URL，改用 canonical/传入 URL
- QbittorrentDownloader: 修复 main() 中模块/类误用导致的 download_by_seed AttributeError；请求加超时
- MySqlService: 修复数据库不可达时 query/execute/close 的 None 崩溃，close 后置空 connection
- 新增 cf_session: Cloudflare 人机认证 cookie 管理 + 限流退避重试 + 自动弹浏览器刷新验证
- 新增 refresh_cf_cookies.py: 弹出浏览器手动验证并保存 cf_clearance
- tests/: 真实网络/数据库测试（get_page、seed_is_exist、cf_session）+ run_tests.py runner
- 清理无用脚本(final_test2/verify_replace/REPLACEMENT_INFO)，.idea 与 cookie 文件入 .gitignore

注: test_qbittorrent_downloader.py 11 个用例为既有失败（mock 目标 session 为实例属性，与实现错配），未在本次范围

dataService/MySqlService.py

@@ -22,9 +22,9 @@ class MySQLDatabase:
     def __enter__(self):
         self.connect()
         return self
-
     def __exit__(self, exc_type, exc_val, exc_tb):
-        self.connection.close()
+        if self.connection and self.connection.open:
+            self.connection.close()
 
     @classmethod
     def create_connection(cls):
@@ -46,9 +46,12 @@ class MySQLDatabase:
     def close(self):
         if self.connection and self.connection.open:
             self.connection.close()
-
+        self.connection = None
     def query(self, sql, params=None):
         self.connect()
+        if not self.connection:
+            logger.error("查询失败：{}，无数据库连接", sql)
+            return None
         with self.connection.cursor() as cursor:
             try:
                 cursor.execute(sql, params or ())
@@ -61,6 +64,9 @@ class MySQLDatabase:
 
     def execute(self, sql, params=None):
         self.connect()
+        if not self.connection:
+            logger.error("执行失败：{}，无数据库连接", sql)
+            return
         with self.connection.cursor() as cursor:
             cursor.execute(sql, params or ())
             self.connection.commit()