feat: harden YamlConfigWatcher for production use

[devspexx]

Summary

Improves the robustness, safety, and performance of the YamlConfigWatcher to make it production-ready.

Changes

• Added retry mechanism for file reads to avoid partial/locked file issues
• Introduced event throttling to prevent excessive reload triggers
• Improved debounce handling for rapid filesystem events
• Added diff size limit to prevent excessive memory usage
• Hardened watcher thread lifecycle and exception handling
• Improved logging for failure scenarios and edge cases
• Ensured safe execution when plugin is disabled

Technical Notes

• Maintains O(n) diff complexity with optimized line parsing
• Avoids regex-based splitting for better performance
• Uses defensive guards against transient filesystem states (delete/recreate)

Result

More stable, predictable, and safe configuration reload behavior under real-world conditions.