When BASE_PATH is set (e.g., /server/), the entrypoint script injects
a <base> tag and rewrites asset paths in index.html. React Router reads
the basename from the <base> tag. Vite builds with relative paths.
Default / for standalone mode (no changes).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
