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/middleware/og.ts

@@ -2,7 +2,7 @@ import { Context, Next } from "@oak/oak";
 import { getDump } from "../services/dump-service.ts";
 import { getUserByUsername } from "../services/user-service.ts";
 import { getPlaylistById } from "../services/playlist-service.ts";
-import { OG_SITE_NAME, SITE_EMOJI } from "../config.ts";
+import { BANDCAMP_PLAYER, OG_SITE_NAME, SITE_EMOJI } from "../config.ts";
 import { emojiToCodepoint } from "../lib/site-icons.ts";
 
 const ICON_VERSION = emojiToCodepoint(SITE_EMOJI);
@@ -69,7 +69,8 @@ async function loadIndexHtml(): Promise<string | null> {
       cachedHtml = (await Deno.readTextFile(path))
         .replaceAll("__SITE_NAME__", OG_SITE_NAME)
         .replaceAll("__SITE_EMOJI__", SITE_EMOJI)
-        .replaceAll("__ICON_VERSION__", ICON_VERSION);
+        .replaceAll("__ICON_VERSION__", ICON_VERSION)
+        .replaceAll("__BANDCAMP_PLAYER__", BANDCAMP_PLAYER);
       return cachedHtml;
     } catch {
       continue;