Unlock everything, add a donation link, credit Last.fm, nudge re-linking

- Every feature is free for everyone (the plan system stays for later);
  remaining limits are abuse guards
- Optional website donation link (NEXT_PUBLIC_DONATION_URL). Not shown in
  the mobile apps, where tips to the developer generally need in-app
  purchase
- Last.fm/ListenBrainz-sourced plays link to the user's profile, as
  Last.fm's API terms require
- Connections track when they last saw activity; a scrobbler silent for
  over a week prompts re-linking Spotify (its link expires every 6 months)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/web/src/components/NowPlayingCard.tsx

@@ -31,7 +31,16 @@ export function NowPlayingCard({
         <span className="row">
           <span className={`status ${np.isPlaying ? 'status-live' : ''}`}>
             {np.isPlaying ? 'Listening now' : `Played ${timeAgo(np.updatedAt)}`}
-            <span className="muted"> via {np.sourceApp ?? SERVICE_LABELS[np.source]}</span>
+            <span className="muted">
+              {' via '}
+              {np.sourceUrl ? (
+                <a href={np.sourceUrl} target="_blank" rel="noreferrer">
+                  {np.sourceApp ?? SERVICE_LABELS[np.source]}
+                </a>
+              ) : (
+                (np.sourceApp ?? SERVICE_LABELS[np.source])
+              )}
+            </span>
           </span>
           {onTogglePin && (
             <button