chore(deploy): Remove temporary postgres port exposure

Port 15432:5432 was added for diagnosis during BARAAA-64. Now that DB
connection is working (POSTGRES_HOST=10.0.9.4) and migrations are
applied, removing the temporary port exposure.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

compose.coolify.yml

@@ -56,8 +56,6 @@ services:
       PGDATA: /var/lib/postgresql/data/pgdata
     volumes:
       - postgres_data_v2:/var/lib/postgresql/data
-    ports:
-      - '15432:5432'
     restart: unless-stopped
     healthcheck:
       test: ['CMD-SHELL', 'pg_isready -U ${POSTGRES_USER:-agenthub} -d ${POSTGRES_DB:-agenthub}']