fix(webmail): keep redirects on the deployment origin

[Mo7ammedd]

Summary

• replace webmail redirects based on the build-time VITE_PUBLIC_APP_URL value with same-origin React Router redirects
• preserve the existing environment configuration and development defaults
• fail release builds if the localhost webmail origin leaks into an executable client bundle

Why

The published webmail image could inline http://localhost:3000 into login, inbox, compose, mailto, and settings redirects. On an HTTPS deployment with its own hostname, those redirects sent the browser to the user's local machine instead of keeping it on the deployed site.

Testing

• bun run build in apps/email/client
• bun run build in apps/email, including the new client bundle portability check
• verified the generated JavaScript contains no VITE_PUBLIC_APP_URL or http://localhost:3000

Notes

The existing client ESLint command cannot start because its configuration imports the unavailable @zero/eslint-config package.