fix: restore essential database configuration for self-hosted deployment

Restore 4 critical lines removed in commit 6ebe974:

1. postgres_data:/var/lib/postgresql/data - Persist database across container recreations
2. ./database/schema:/docker-entrypoint-initdb.d - Auto-load schema on first startup
3. ports: - "5432:5432" - Expose DB to host for integration tests and direct access
4. env_file: - .env - Load environment configuration

These are required for:
- Self-hosted production deployments
- Data persistence across docker-compose up -d --build
- Automatic database initialization on new machines
- Integration test execution (localhost:5432 access)

Fixes integration tests that fail with "connection refused"

docker-compose.yml

@@ -10,12 +10,18 @@ services:
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD: ${DBPASS}
     volumes:
+      - postgres_data:/var/lib/postgresql/data
+      - ./database/schema:/docker-entrypoint-initdb.d
       - ./uploads:/app/uploads
+    ports:
+      - "5432:5432"
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U postgres"]
       interval: 5s
       timeout: 5s
       retries: 3
+    env_file:
+      - .env
 
   # Bookhoard Application
   app:
@@ -61,4 +67,5 @@ services:
 
 # Named Volumes
 volumes:
+  postgres_data:
   bookhoard_conversion_cache: