Builds now emit version.json + a __BUILD_VERSION__ define. The client
re-checks the remote version on visibilitychange/focus and reloads on
mismatch, so a backgrounded tab doesn't hit a 404'd hashed chunk and
surface "'text/html' is not a valid JavaScript MIME type" when opening
Settings. ErrorBoundary catches stale-chunk errors as a safety net.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
