Improve logger thread safety

[themuffinator]

Summary

• protect logger configuration updates with a mutex and log level with an atomic
• guard initialization, log level changes, and sink formatting through thread-safe snapshots
• add a concurrency-focused logger test covering sink formatting stability

Testing

• g++ -std=c++23 -Isrc -pthread src/shared/logger.cpp tests/test_logger_thread_safety.cpp -o /tmp/test_logger

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Update thread safety test to drive error sink

The new thread-safety test asserts g_errorMessages is non-empty, but the only logging performed in this test uses worr::Log (lines 64‑67), which routes messages to the print sink only; the error sink is driven exclusively by LoggerError. Because CollectError is never invoked, g_errorMessages will always remain empty and the assertion here fails deterministically. The test needs to call LoggerError (or drop the assertion) to reflect the logger API.

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