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

config.py

@@ -418,7 +418,7 @@ def reload_config() -> dict:
 # 邮箱系统选择
 EMAIL_PROVIDER = _cfg.get("email_provider", "kyx")  # "kyx" 或 "gptmail"
 
-# 原有邮箱系统 (KYX)
+# 原有邮箱系统 (KYX / Cloud Mail)
 _email = _cfg.get("email", {})
 EMAIL_API_BASE = _email.get("api_base", "")
 EMAIL_API_AUTH = _email.get("api_auth", "")
@@ -427,6 +427,17 @@ EMAIL_DOMAIN = EMAIL_DOMAINS[0] if EMAIL_DOMAINS else ""
 EMAIL_ROLE = _email.get("role", "gpt-team")
 EMAIL_WEB_URL = _email.get("web_url", "")
 
+
+def get_cloudmail_api_base() -> str:
+    """获取 Cloud Mail API 地址，自动补全 /api/public 路径"""
+    if not EMAIL_API_BASE:
+        return ""
+    api_base = EMAIL_API_BASE.rstrip("/")
+    if not api_base.endswith("/api/public"):
+        api_base = f"{api_base}/api/public"
+    return api_base
+
+
 # GPTMail 临时邮箱配置
 _gptmail = _cfg.get("gptmail", {})
 GPTMAIL_API_BASE = _gptmail.get("api_base", "https://mail.chatgpt.org.uk")