migrations: fix jellyfin id DDL for h2 compatibility

src/main/resources/db/migration/V5__add_jellyfin_id_columns.sql

@@ -1,12 +1,17 @@
 -- Add jellyfin_id columns for mapping between MovieNight and Jellyfin
 ALTER TABLE films
-    ADD COLUMN jellyfin_id UUID UNIQUE NULL,
-    ADD COLUMN jellyfin_library_id UUID NULL;
+    ADD COLUMN jellyfin_id UUID;
+
+ALTER TABLE films
+    ADD CONSTRAINT uq_films_jellyfin_id UNIQUE (jellyfin_id);
 
 CREATE INDEX idx_films_jellyfin_id ON films(jellyfin_id);
 
 -- Add jellyfin_id to users for sync mapping
 ALTER TABLE users
-    ADD COLUMN jellyfin_id UUID UNIQUE NULL;
+    ADD COLUMN jellyfin_id UUID;
+
+ALTER TABLE users
+    ADD CONSTRAINT uq_users_jellyfin_id UNIQUE (jellyfin_id);
 
 CREATE INDEX idx_users_jellyfin_id ON users(jellyfin_id);