feat(config,email_service): Add Cloud Mail API path auto-completion utility

- Add get_cloudmail_api_base() helper function to automatically append /api/public path to EMAIL_API_BASE
- Update create_email_user() to use get_cloudmail_api_base() for consistent API endpoint construction
- Update get_verification_code() to use get_cloudmail_api_base() for email list retrieval
- Update fetch_email_content() to use get_cloudmail_api_base() for email list retrieval
- Refactor telegram_bot.py to use centralized path completion logic instead of inline implementation
- Improve API endpoint consistency across email service operations and reduce code duplication

telegram_bot.py

@@ -4506,7 +4506,12 @@ class ProvisionerBot:
                 if not EMAIL_DOMAINS:
                     return False, "未配置 email.domains"
                 
-                url = f"{EMAIL_API_BASE}/emailList"
+                # 自动补全 /api/public 路径
+                api_base = EMAIL_API_BASE.rstrip("/")
+                if not api_base.endswith("/api/public"):
+                    api_base = f"{api_base}/api/public"
+                
+                url = f"{api_base}/emailList"
                 headers = {
                     "Authorization": EMAIL_API_AUTH,
                     "Content-Type": "application/json"