Migrates 5 SILENT_SWALLOW sites to full Result[T] pattern:
session_logger.py (4 sites):
1. log_api_hook - returns Result[bool] (was None)
2. log_comms - returns Result[bool] (was None)
3. log_tool_call - returns Result[Optional[str]] (was Optional[str])
4. log_cli_call - returns Result[bool] (was None)
file_cache.py (1 site):
- L98: removed dead code (try/except StopIteration around
next(iter(_ast_cache)) is unreachable because we just checked
len(_ast_cache) >= 10)
Updates tests/test_session_logger_optimization.py to extract
result.data from the new Result-based API.
All callers of these log_* functions previously ignored the
return value; they continue to ignore the new Result return
value (backwards-compatible).