security: remove hardcoded POSTGRES_PASSWORD from docker-compose

Replace literal password with \${POSTGRES_PASSWORD} env var reference.
Password must be set in .env file (already gitignored).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

docker-compose.yaml

@@ -42,7 +42,7 @@ services:
     ports:
       - 5432:5432
     environment:
-      - POSTGRES_PASSWORD=090271jd
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
     volumes:
       - postgres_data:/var/lib/postgresql/data
     expose: