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/hooks/usePlayRichContent.ts

@@ -0,0 +1,86 @@
+import { useCallback, useContext, useState } from "react";
+import { PlayerContext, type PlayerItem } from "../contexts/PlayerContext.ts";
+import { BANDCAMP_PLAYER } from "../config/playerMode.ts";
+import { resolveBandcampQueue } from "../utils/bandcamp.ts";
+
+export interface PlayableRichContent {
+  type: string;
+  url: string;
+  title?: string;
+  embedUrl?: string;
+  /** Header artwork. Callers with a dump-level override should pass that. */
+  thumbnailUrl?: string;
+  /** Header subtitle — "YouTube", "SoundCloud", the site's own name. */
+  siteName?: string;
+}
+
+/**
+ * Start playback for a rich-content item.
+ *
+ * Everything except Bandcamp goes straight to the iframe embed, exactly as
+ * before. Bandcamp additionally honours GERBEUR_BANDCAMP_PLAYER: in "native"
+ * mode the page is resolved to its mp3 streams and played as a queue, which is
+ * what makes it autoplay and lets albums play through. Any failure — offline,
+ * preorder-only release, Bandcamp changing its markup — silently falls back to
+ * the embed, so this can never leave a card unplayable.
+ */
+export function usePlayRichContent() {
+  const { play, playQueue } = useContext(PlayerContext);
+  const [pending, setPending] = useState(false);
+
+  const playEmbed = useCallback(
+    (rc: PlayableRichContent, dumpHref?: string) => {
+      if (!rc.embedUrl) return;
+      play({
+        kind: "embed",
+        embedUrl: rc.embedUrl,
+        title: rc.title,
+        type: rc.type,
+        dumpHref,
+        artworkUrl: rc.thumbnailUrl,
+        subtitle: rc.siteName,
+      });
+    },
+    [play],
+  );
+
+  const playRichContent = useCallback(
+    async (rc: PlayableRichContent, dumpHref?: string) => {
+      const native = rc.type === "bandcamp" && BANDCAMP_PLAYER === "native";
+      if (!native) {
+        playEmbed(rc, dumpHref);
+        return;
+      }
+
+      setPending(true);
+      try {
+        const items: PlayerItem[] = await resolveBandcampQueue(rc.url, {
+          dumpHref,
+          embedUrl: rc.embedUrl,
+          // Bandcamp's own album art wins; this is the fallback if the page
+          // doesn't carry one.
+          fallbackArtworkUrl: rc.thumbnailUrl,
+        });
+        playQueue(items, 0);
+      } catch (err) {
+        console.warn("bandcamp: native playback unavailable, using embed", err);
+        playEmbed(rc, dumpHref);
+      } finally {
+        setPending(false);
+      }
+    },
+    [playEmbed, playQueue],
+  );
+
+  return { playRichContent, pending };
+}
+
+/**
+ * Whether a rich-content item can be played at all. In native mode a Bandcamp
+ * page is playable even without a stored embedUrl, since the streams are
+ * resolved from the page itself.
+ */
+export function canPlayRichContent(rc: PlayableRichContent): boolean {
+  if (rc.embedUrl) return true;
+  return rc.type === "bandcamp" && BANDCAMP_PLAYER === "native";
+}