🎉 Add frame thumbnail API

backend/src/app/migrations/sql/0066-add-frame-thumbnail-table.sql

@@ -0,0 +1,10 @@
+CREATE TABLE file_frame_thumbnail (
+  file_id uuid NOT NULL REFERENCES file(id) ON DELETE CASCADE,
+  frame_id uuid NOT NULL,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  updated_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+
+  data text NULL,
+
+  PRIMARY KEY(file_id, frame_id)
+);