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.

cf-email-worker/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "grok-xai-mail-codes",
+  "private": true,
+  "scripts": {
+    "deploy": "wrangler deploy",
+    "dev": "wrangler dev"
+  },
+  "devDependencies": {
+    "wrangler": "^3.99.0"
+  }
+}