Fix: Comprehensive codebase health check and cleanup

[rwkeane]

This commit addresses multiple aspects of codebase health:

1. Test Failures:

   • Resolved 3 failing tests in tsercom/runtime_e2etest.py related to out-of-process error propagation and handling. The fixes involved improving synchronization using multiprocessing.Event to ensure child process errors are reliably detected by the parent RuntimeManager. Affected tests:
     • test_out_of_process_error_check_for_exception
     • test_out_of_process_error_run_until_exception
     • test_out_of_process_initializer_create_error

2. Overload Docstrings:

   • Ensured all functions using @typing.overload (aliased as @overload) have complete Google-style docstrings for each individual overload signature and for the main implementation. This involved adding or verifying docstrings in files such as:
     • tsercom/api/runtime_handle.py
     • tsercom/runtime/runtime_data_handler.py
     • tsercom/runtime/runtime_data_handler_base.py
     • tsercom/tensor/demuxer/stream_receiver.py
     • tsercom/tensor/muxer/aggregate_tensor_multiplexer.py
   • Files like tsercom/data/remote_data_aggregator.py, tsercom/data/remote_data_aggregator_impl.py, tsercom/discovery/discovery_host.py, tsercom/runtime/endpoint_data_processor.py, and tsercom/runtime/id_tracker.py, tsercom/runtime/runtime_config.py were reviewed and found to already have compliant overload documentation.

3. Ruff Issues:

   • Added D418 (Function decorated with @overload is missing a docstring) to the ignore list in pyproject.toml as the main implementation docstrings are intentionally brief when overloads are fully documented.
   • Ran ruff check . --fix to automatically correct applicable issues.
   • Manually addressed remaining Ruff violations, including:
     • E501 (Line too long) by shortening docstrings, comments, and code lines.
     • D401 (First line of docstring should be in imperative mood).
     • Other D series docstring convention errors (D100, D101, D102, D103, D105, D107, D203, D205, D210, D211, D212, D213, D404, D413, D417).
     • W293 (Blank line contains whitespace).
   • Corrected syntax errors that were inadvertently introduced during manual E501 fixes by ensuring docstrings were properly formatted.
   • The codebase now passes ruff check . cleanly.

4. Static Analysis and Verification:

   • Ran black . to format the code.
   • mypy tsercom/ was run; identified errors were pre-existing and not introduced by these changes.
   • The full test suite (pytest --timeout=120) was run twice successfully after all changes to ensure no regressions.

This work improves test reliability, documentation quality, and code style adherence across the tsercom/ codebase.