Database Layer & Migrations

[onelrian]

• Priority: HIGH | Effort: LARGE | Dependencies: TICKET-001
• Acceptance Criteria:
  • PostgreSQL schema implemented (auth + business tables)
  • SQLx integration with connection pooling
  • Migration system with rollback support
  • Data migration from existing JSON files
  • Database seeding for development
  • Indexes optimized for query performance
  • Backup and recovery procedures documented
• Files: backend/src/database/, migrations/, migration scripts