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

src/themes/geocities.css

@@ -496,6 +496,13 @@
   border-radius: 0;
 }
 
+/* Queue UI: square off the artwork and the stream progress bar. */
+[data-style="geocities"] .global-player-artwork,
+[data-style="geocities"] .audio-player-track--stream::before,
+[data-style="geocities"] .audio-player-track--stream .audio-player-fill {
+  border-radius: 0;
+}
+
 [data-style="geocities"] .global-player .audio-player-btn {
   color: var(--color-on-accent);
 }