All backend PHP files require config.php as their first include.
It was gitignored and missing, causing PHP fatal errors that produced
empty responses — breaking JSON parsing in the frontend.
The new config.php has no hardcoded secrets; it reads all values
(GEMINI_API_KEY, KLING_ACCESS_KEY, KLING_SECRET_KEY, SSO_*) from
the .env file via env_loader.php.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
