Backfill slide thumbnail migration

src/db/migrations.js

@@ -732,6 +732,15 @@ const migrations = [
       await addColumnIfMissing(pool, 'playlists', 'skip_unavailable_rtmp', 'TINYINT(1) NOT NULL DEFAULT 0');
     }
   },
+  {
+    key: 'slides-thumbnail-path-column',
+    version: appVersion,
+    comment: 'Backfill the slides.thumbnail_path column for databases that already recorded the broader schema migration.',
+    order: 22,
+    up: async function (pool) {
+      await addColumnIfMissing(pool, 'slides', 'thumbnail_path', 'VARCHAR(512) NULL');
+    }
+  },
   {
     key: 'media-path-prefix-rename',
     version: appVersion,