Add Gmail+Email Worker hybrid mail path and private runtime config

Prefer Cloudflare Worker KV for verification codes with optional short IMAP
fallback disabled for private deploy; track config.json/.env for private repo.
Also add worker project, protocol mint backoff, and fail-fast Turnstile/mail
timeouts from batch runs.

.env.example

@@ -6,6 +6,11 @@
 # 配合 Cloudflare catch-all 域名使用；密码填 Gmail「应用专用密码」
 GMAIL_USER=
 GMAIL_PASSWORD=
+
+# ===== Gmail + Cloudflare Email Worker（秒级取码，IMAP 兜底）=====
+# 部署见 cf-email-worker/README.md
+# GMAIL_WORKER_URL=https://grok-xai-mail-codes.<subdomain>.workers.dev
+# GMAIL_WORKER_API_KEY=
 # 兼容别名（gmail_code_listener 会回退读取）
 # MAIL_USER=
 # MAIL_PASSWORD=