fix: make trigger creation idempotent

- Add DROP TRIGGER IF EXISTS before CREATE TRIGGER
- Fixes 'trigger already exists' error during schema initialization
- Allows schema to run multiple times safely

database/schema/schema.sql

@@ -443,6 +443,7 @@ END;
 $$ LANGUAGE plpgsql;
 
 -- Trigger for devices table
+DROP TRIGGER IF EXISTS update_devices_updated_at ON devices;
 CREATE TRIGGER update_devices_updated_at
   BEFORE UPDATE ON devices
   FOR EACH ROW