fix: remove duplicate updated_at column from V5 migration

apps.updated_at already exists from V3. The duplicate ALTER caused
Flyway to fail on startup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/db/migration/V5__app_container_config.sql

@@ -1,5 +1,4 @@
 -- Add container config to apps and environment defaults
 ALTER TABLE apps ADD COLUMN container_config JSONB NOT NULL DEFAULT '{}';
-ALTER TABLE apps ADD COLUMN updated_at TIMESTAMPTZ NOT NULL DEFAULT now();
 
 ALTER TABLE environments ADD COLUMN default_container_config JSONB NOT NULL DEFAULT '{}';