Comments on plays

- Anyone who can see a play can read its comments; the player and the people they follow can write.
  The author, the player and admins can delete; comments can be reported (admins see the text).
- Notifications: "commented on" for the player, "replied on" for earlier commenters, each with its
  own setting. Reaction and comment notifications now open the play.
- A 💬 chip with the count next to reactions on the feed and recent plays, opening the thread on
  the app (/play/[id]) and the website. Threads refresh every few seconds while open.
- Blocking removes comments between the two people. Plays with comments survive history trimming.
- Privacy page updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011Y2iUsKEWDuRGjK5FPmcUP

packages/shared/src/notifications.test.ts

@@ -17,11 +17,22 @@ describe('notifications', () => {
   });
 
   it('links songs to the song and follows to the person', () => {
-    expect(notificationPath({ type: 'share', actor, track })).toBe('/t/t1');
-    expect(notificationPath({ type: 'follow', actor, track: null })).toBe('/u/bob');
+    expect(notificationPath({ type: 'share', actor, track, listenId: null })).toBe('/t/t1');
+    expect(notificationPath({ type: 'follow', actor, track: null, listenId: null })).toBe('/u/bob');
+  });
+
+  it('opens the play for comments, replies and reactions', () => {
+    expect(notificationPath({ type: 'comment', actor, track, listenId: 'l1' })).toBe('/play/l1');
+    expect(notificationPath({ type: 'reaction', actor, track, listenId: 'l1' })).toBe('/play/l1');
+    // The play was trimmed from history: fall back to the song.
+    expect(notificationPath({ type: 'reaction', actor, track, listenId: null })).toBe('/t/t1');
+    expect(notificationText({ type: 'reply', actor, track, emoji: null, message: 'same' })).toEqual({
+      title: 'Bob replied on Teardrop by Massive Attack',
+      body: 'same',
+    });
   });
 
   it('treats missing settings as on', () => {
-    expect(notificationPrefs({ follow: false })).toEqual({ reaction: true, follow: false, share: true });
+    expect(notificationPrefs({ follow: false })).toEqual({ reaction: true, comment: true, reply: true, follow: false, share: true });
   });
 });