Fix Config Race Condition and Logger Split-Brain

[google-labs-jules]

This PR addresses critical concurrency issues in the configuration and logging subsystems.

Configuration Fixes

• Race Condition: The Config struct in internal/config/config.go was vulnerable to data races where fields were read while being written (e.g., by the orchestrator).
• Solution: Added a sync.RWMutex to the Config struct. All method implementations of the Interface (Getters and Setters) now strictly use RLock() and Lock() respectively to ensure thread safety.

Logger Fixes

• Split-Brain Logging: Previously, if GetLogger() was called before Initialize(), the caller received a fallback logger and would hold onto it indefinitely, ignoring the subsequent initialization.
• Solution: Implemented the Proxy Pattern. GetLogger() now returns a stable singleton proxyLogger backed by a proxyCore. This core delegates dynamically to the underlying globalLogger, ensuring that when Initialize() runs, all existing references effectively "hot-swap" to the new configuration.
• Unsafe Test Reset: The ResetForTest function was overwriting a sync.Once value, which is unsafe.
• Solution: Replaced sync.Once with atomic.Pointer[sync.Once], allowing safe and atomic resetting of initialization state for tests.

Verification

• Added/Updated unit tests in pkg/observability to verify the proxy behavior and initialization logic.
• Ran existing tests for internal/config (failures unrelated to these changes were noted but out of scope).

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PR created automatically by Jules for task 3017510955809941058 started by @xkilldash9x

[google-labs-jules]

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