Implement Factory for order handlers & Adapter for DB repo (LOW) - add Factory and Adapter patterns for order handling and repositories

[raggopaluni]

Goal:

• Abstract creation of order handlers and DB repository adapters to prepare for new order types.

Tasks:

• Implement services/patterns/factory.py to return OrderHandler instances (for now one VMwareOrderHandler).
• Ensure API code uses Factory to get handler and call handler.create_order(body).
• Ensure repository access is via Adapter interface (OrderRepository) implemented by PostgresAdapter + MongoAdapter.

Acceptance criteria:

• API layer no longer directly calls DB clients; uses handler -> repository interfaces.
• Unit tests should be easier to mock.