[codex] close out API transport protocol work

[ObservedObserver]

Summary

• Tighten the reusable Walker API path across adapters and derive conflict defaults from the public signatures.
• Alias deprecated legacy Jupyter transports to the anywidget transport with explicit PyGWalker 0.7.0 removal warnings.
• Generate frontend communication protocol TypeScript types from the Python Pydantic protocol models and add contract coverage.

Impact

This keeps existing public entry points working while moving legacy Jupyter usage onto the supported anywidget path. It also reduces frontend/backend protocol drift by making the generated TypeScript contract verifiable from Python.

Validation

• venv/bin/python -m pytest tests/test_computation.py tests/test_integration_apis.py tests/test_walker_api.py tests/test_pygwalker_core.py tests/test_readme_api_reference.py tests/test_frontend_contracts.py tests/test_communication_transports.py tests/test_data_communication.py tests/test_cloud_communication.py tests/test_spec_communication.py -q --disable-warnings (210 passed)
• venv/bin/python -m ruff check README.md pygwalker/api/_walker_reuse.py pygwalker/api/anywidget.py pygwalker/api/html.py pygwalker/api/jupyter.py pygwalker/api/marimo.py pygwalker/api/streamlit.py pygwalker/api/walker.py pygwalker/api/webserver.py pygwalker/communications/protocol.py pygwalker/utils/computation.py scripts/generate_comm_protocol_ts.py tests/test_computation.py tests/test_frontend_contracts.py tests/test_integration_apis.py tests/test_pygwalker_core.py tests/test_readme_api_reference.py tests/test_walker_api.py
• yarn typecheck from app/
• venv/bin/python scripts/generate_comm_protocol_ts.py followed by no diff in app/src/interfaces/comm.generated.ts