Origin validation, every rate limiter and the password-strength check each
treated an unset PUBLIC_BUILD_ENV as "relaxed", so a deployment that forgot the
variable silently ran with CORS reflecting any origin, no brute-force limit on
the sole account, and no password rules. setup.sh writes it, but .env.example
never mentioned it.
The three now share IS_DEV_BUILD, which is true only when PUBLIC_BUILD_ENV is
explicitly "dev" or "development". Anything else, including unset, is hardened.
Documented in .env.example.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
