nginx has no MIME type for .mjs, so the pdf.js worker was served as
application/octet-stream and browsers refused to load it. Every imported
PDF page then showed "Source PDF ... is not available", which looked like
missing files. Serve .mjs as text/javascript.
The page background now also tells the two failures apart: "not stored on
this device" when the source bytes are missing, and "could not display"
(with the error logged) when pdf.js fails.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VsorPV3JeJRoZ1mD1pdvtL
Multi-stage build: Node builds the static PWA, nginx serves it with an SPA
fallback, long-lived caching for hashed assets, no-cache for the app shell
and service worker, and the correct type for the web manifest.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VsorPV3JeJRoZ1mD1pdvtL
