Initial build: fullhouse, live music bingo from a real Spotify playlist

Based on bingo-bango by f8al (MIT) — same core card-generation idea
("both facets": a square is either an exact song title or an artist,
and an artist square lights up on any of their tracks), reworked with
a real host/guest split, live multiplayer sessions, and cover-art
squares. f8al credited in the footer, README, and PROPOSAL.md.

Three ways to play: host a live session (server-side Spotify
connection, join code + QR, caller screen, auto-call from real
playback), join someone else's session (no login needed), or solo
(guest PKCE login or a pasted public playlist URL, one-off card).

Genuinely verified against a real Spotify account throughout, not
just built and assumed working — including two real bugs found and
fixed along the way (Spotify's playlist-tracks endpoint quietly
renamed to /items with a reshaped response; reading playlist tracks
needs real user auth even for public playlists, so the "no guest
login" public-playlist path routes through the host's connection
instead of a dead-end app-only token). Both Docker images built and
run together on a real network with the nginx proxy verified working
end-to-end, and auto-call confirmed detecting an actual track playing
live through Spotify Connect within one poll tick.

client/tsconfig.json

@@ -0,0 +1,18 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "types": ["vite/client"]
+  },
+  "include": ["src"]
+}