feat(gif): favourites and category shortcuts

Favourites are stored server-side per user, so one made on the phone is there
on the desktop — the point of favouriting. The whole result is stored rather
than an id: the provider offers no lookup by id, so an id-only favourite could
not be rendered without re-finding it through search.

Category chips translate their label but not their query, which goes to a
provider that indexes in English.

The star sits beside the tile button rather than inside it: a button within a
button is invalid and swallows the click. Toggling is optimistic and reverts
on failure, and favourites skip both the loading skeleton and the infinite
scroll, which belong to provider-backed browsing only.

Server caps favourites per user and rejects non-http(s) URLs, which become
<img src> in everyone's picker.

packages/server/src/db/schema.ts

@@ -566,3 +566,24 @@ export const spotifyConnections = sqliteTable('spotify_connections', {
   spotifyUserId: text('spotify_user_id'),
   createdAt: integer('created_at').notNull(),
 });
+
+/**
+ * Favourited GIFs, one row per user per GIF.
+ *
+ * Stores the whole result rather than an id: the provider offers no lookup by
+ * id, so a favourites tab that only kept ids could not render without
+ * re-searching for something the user may never find again.
+ */
+export const gifFavorites = sqliteTable('gif_favorites', {
+  userId: text('user_id').notNull().references(() => users.id, { onDelete: 'cascade' }),
+  gifId: text('gif_id').notNull(),
+  title: text('title').notNull(),
+  previewUrl: text('preview_url').notNull(),
+  url: text('url').notNull(),
+  width: integer('width').notNull(),
+  height: integer('height').notNull(),
+  createdAt: integer('created_at').notNull(),
+}, (table) => ({
+  pk: primaryKey({ columns: [table.userId, table.gifId] }),
+  userIdx: index('idx_gif_favorites_user_id').on(table.userId),
+}));