nginx regex locations outrank prefix locations, so app-shell assets like
/app/bitcoin-core/tailwind.css and /app/lnd/qrcode.js hit the .css/.js
cache block and 404'd from the web root instead of proxying to the mock
backend — the actual cause of the unstyled Bitcoin UI (and the shabby
lnd-ui) on the demo. ^~ on the /app/ prefixes disables regex matching
for those paths. Config validated with nginx -t.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>