fix(demo): iframe mempool+indeehub directly, serve real UIs statically, AIUI canned

- Mempool and IndeeHub load their real site directly in the iframe (reverted the
  proxy/new-tab — per request "use https://indee.tx1138.com/").
- Real app UIs now served as whole static dirs under /app/<id>/ (express.static)
  so their bundled assets (qrcode.js, css, bg images) resolve; /app/<id>/assets/*
  redirect to the frontend's shared assets. Fixes the console 404 cascade.
- Bitcoin Core/Knots: register rpc/v1 + bitcoin-rpc on their paths (relay-status
  no longer 404s); per-impl bitcoin-status preserved.
- AIUI chat returns a fixed line in demo ("Not available in demo, check out the
  previous chats to experience AIUI") instead of calling Claude — no key spend.
- Add /api/app-catalog (serves the baked catalog) to stop that 404.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/docker/nginx-demo.conf

@@ -94,19 +94,6 @@ http {
             proxy_request_buffering off;
         }
 
-        # IndeeHub: reverse-proxy the real site same-origin and strip its
-        # X-Frame-Options / CSP so it can load inside the in-app iframe.
-        location /app/indeedhub/ {
-            proxy_pass https://indee.tx1138.com/;
-            proxy_http_version 1.1;
-            proxy_set_header Host indee.tx1138.com;
-            proxy_ssl_server_name on;
-            proxy_set_header Accept-Encoding "";
-            proxy_hide_header X-Frame-Options;
-            proxy_hide_header Content-Security-Policy;
-            proxy_hide_header Content-Security-Policy-Report-Only;
-        }
-
         # Proxy every other app UI (/app/<id>/) to the mock backend, which serves
         # the per-app mock UIs (bitcoin-ui, electrumx, lnd, fedimint) and the
         # generic "Not available in the demo" notice for the rest.