Emoji reactions on songs

React to a friend's current song or any of their recent plays: tap an
emoji to add yours (or take it back), "☺+" for the quick six, and a full
picker with search and categories (Unicode emoji up to 13.1, generated
into the shared package so web and mobile match). One reaction per person
per play; a new one replaces the old. Chips show counts and, on hover/
long label, who reacted; yours is highlighted. Listeners and followers get
the update live. Not on your own plays, not across a block (blocking also
clears reactions between the two people).

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

apps/api/src/db/schema.ts

@@ -242,6 +242,22 @@ export const featuredSongs = pgTable('featured_songs', {
     .default(sql`now()`),
 });
 
+/** One emoji per person per play. Deleted with the play (only the latest 50 plays are kept). */
+export const reactions = pgTable(
+  'reactions',
+  {
+    listenId: uuid('listen_id')
+      .notNull()
+      .references(() => listens.id, { onDelete: 'cascade' }),
+    userId: uuid('user_id')
+      .notNull()
+      .references(() => users.id, { onDelete: 'cascade' }),
+    emoji: varchar('emoji', { length: 32 }).notNull(),
+    createdAt: createdAt(),
+  },
+  (t) => [primaryKey({ columns: [t.listenId, t.userId] })],
+);
+
 /** Email confirmation links (sign-up and email changes). Only a hash of the token is stored. */
 export const emailVerifications = pgTable(
   'email_verifications',