Add CreateTransaction operation and models to Ledger API client

[jfrench9]

Summary

Introduces the CreateTransaction operation for the Robo Ledger API, including new request/status models and client integration. This feature enables consumers of the robosystems_client to create transactions through the ledger service.

Key Accomplishments

• New API Operation: Added op_create_transaction.py implementing the full create transaction operation within the extensions_robo_ledger API module, including request construction, serialization, and response handling (~289 lines).
• New Data Models:
  • CreateTransactionRequest — comprehensive model representing the transaction creation payload with full serialization/deserialization support (~248 lines).
  • CreateTransactionRequestStatus — enum/status model representing the possible states of a create transaction request.
• Ledger Client Integration: Extended LedgerClient with methods to invoke the new create transaction operation, providing a clean high-level interface for callers.
• Model Registry: Updated models/__init__.py to export the new CreateTransactionRequest and CreateTransactionRequestStatus models, ensuring they are discoverable and importable from the top-level models package.

Breaking Changes

None. This is a purely additive change — new files and new methods on the existing LedgerClient. No existing interfaces or models were modified in a backward-incompatible way.

Testing Notes

• Verify that CreateTransactionRequest correctly serializes to the expected API payload format and deserializes responses properly.
• Test CreateTransactionRequestStatus enum values cover all states returned by the backend.
• Validate the LedgerClient create transaction method end-to-end against a running or mocked Ledger API instance.
• Ensure edge cases are handled (e.g., missing/optional fields in the request model, error responses from the API).

Infrastructure Considerations

• This feature depends on corresponding backend support for the create transaction endpoint in the Robo Ledger service. Ensure the target API version is deployed before consuming this client functionality.
• No new dependencies are introduced; the implementation follows existing patterns in the client library.

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Branch Info:

• Source: feature/create-transaction-op
• Target: main
• Type: feature

Co-Authored-By: Claude noreply@anthropic.com