fix(log): Add error handling for file sync and close operations

[justin-layerv]

Summary

Add error handling for file.Sync() and file.Close() operations in the async log writer.

Problem

The writeRoutine() function in AsyncLogWriter was not checking errors from:

• file.Sync() - could fail if disk is full or I/O error occurs
• file.Close() - could indicate buffered writes didn't flush properly

According to Go best practices, errors from closing writable files should be checked as they can indicate data loss.

Changes

File	Change
nhp/log/logger.go	Add error handling for file.Sync() and file.Close()

Test plan

• Verify build passes
• Verify logging still works correctly
• Error messages are printed when sync/close fails (e.g., disk full scenario)

🤖 Generated with Claude Code

[craftleon]

Merging is blocked due to commit missing verified signatures