v3: native bandcamp playback and a queue in the global player

The player now holds a queue instead of a single item, so albums play
through and single tracks share the same code path. Adds a "stream" item
kind for expiring, remotely-hosted sources: Bandcamp signs its mp3 URLs
for ~24h, so an item carries the page it came from and re-resolves itself
on error or on a stale restored session, falling back to the iframe embed
if that fails too.

Gated behind GERBEUR_BANDCAMP_PLAYER (default "embed"), injected into a
meta tag the same way as site-name/site-emoji.

Also: player header gains artwork and a subtitle, volume persists across
queue advances and reloads, and cross-origin streams get a plain seek bar
rather than a waveform that can never decode.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SbtjNsT5wvuABnfqhegZEJ

api/main.ts

@@ -9,6 +9,7 @@ import usersRouter from "./routes/users.ts";
 import avatarsRouter from "./routes/avatars.ts";
 import wsRouter from "./routes/ws.ts";
 import previewRouter from "./routes/preview.ts";
+import bandcampRouter from "./routes/bandcamp.ts";
 import playlistsRouter from "./routes/playlists.ts";
 import commentsRouter from "./routes/comments.ts";
 import chatRouter from "./routes/chat.ts";
@@ -71,6 +72,10 @@ app.use(
   previewRouter.routes(),
   previewRouter.allowedMethods(),
 );
+app.use(
+  bandcampRouter.routes(),
+  bandcampRouter.allowedMethods(),
+);
 app.use(
   playlistsRouter.routes(),
   playlistsRouter.allowedMethods(),