feat: add modpack update tracking feature

scripts/migrations/002_modpacks_updated_at.sql

@@ -0,0 +1,6 @@
+ALTER TABLE modpacks ADD COLUMN updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW();
+
+CREATE TRIGGER set_timestamp_modpacks
+BEFORE UPDATE ON modpacks
+FOR EACH ROW
+EXECUTE FUNCTION trigger_set_timestamp();