mailtmp backend

Cloudflare Worker temporary-email backend with sonzaix-like endpoints.

• POST /api/auth - create/login mailbox
• GET /api/domains - list available domains
• GET /api/messages?address=...&password=... - list messages
• GET /api/messages/:id?address=...&password=... - get message detail
• DELETE /api/delete-account?address=...&password=... - delete mailbox