fix: configure PostgreSQL for production and clean up deployment

- Fix database configuration to use PostgreSQL in production
- Add knexfile.js to support both SQLite (dev) and PostgreSQL (prod)
- Create admin user creation script (scripts/create-admin.js)
- Clean up docker-compose files:
  - Remove redundant docker-compose.yml and docker-compose.local.yml
  - Create docker-compose.dev.yml for development
  - Update docker-compose.prod.yml with proper DB configuration
- Clean up environment files:
  - Update .env.example for development
  - Update .env.production.example with proper settings
  - Remove redundant .env.local
- Update backend .env.example with database configuration options
- Create comprehensive DEPLOYMENT.md with admin setup instructions
- Fix production database name consistency (picpeak instead of photoapp)

backend/.env.example

@@ -24,10 +24,19 @@ ARCHIVE_PATH=./storage/events/archived
 # Logging
 LOG_LEVEL=info
 
-# Database (for production, consider PostgreSQL)
+# Database Configuration
+# Development: Use SQLite
 DATABASE_CLIENT=sqlite3
 DATABASE_PATH=./data/photo_sharing.db
 
+# Production: Use PostgreSQL
+# DATABASE_CLIENT=pg
+# DB_HOST=localhost
+# DB_PORT=5432
+# DB_USER=picpeak
+# DB_PASSWORD=your-secure-password
+# DB_NAME=picpeak
+
 # Umami Analytics (optional)
 UMAMI_URL=
 UMAMI_WEBSITE_ID=