修改IMAP默认服务器地址为统一代理

- 移除旧的 bdhg.xyz 等默认域名映射
- 未匹配的邮箱域名统一使用 111.229.206.54 IMAP代理

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/douyu/email_verifier.py

@@ -334,9 +334,8 @@ class EmailVerifier:
 
 
 def get_email_config_for_account(email_address: str) -> dict:
-    """根据邮箱地址自动配置IMAP服务器"""
+    """根据邮箱地址自动配置IMAP服务器，默认使用统一IMAP代理"""
     configs = {
-        'bdhg.xyz': {'server': 'mail.bdhg.xyz', 'port': 993},
         'qq.com': {'server': 'imap.qq.com', 'port': 993},
         '163.com': {'server': 'imap.163.com', 'port': 993},
         '126.com': {'server': 'imap.126.com', 'port': 993},
@@ -346,4 +345,4 @@ def get_email_config_for_account(email_address: str) -> dict:
     }
 
     domain = email_address.split('@')[-1].lower()
-    return configs.get(domain, {'server': f'imap.{domain}', 'port': 993})
+    return configs.get(domain, {'server': '111.229.206.54', 'port': 993})