Improve policy bot rules: regex modernization, label coverage, and cleanup

[denelon]

Summary

Improve the winget-cli policy bot rules so label handling, regex matching, and cleanup flows behave consistently.

Requested changes

• Modernize regex patterns to use (?in) inline flags.
• Fix triageLabels so auto-applied labels do not clear triage prematurely.
• Remove unused automergeTriggers entries.
• Add Needs-Author-Feedback back to triageLabels.
• Clean up related stale and moderation flow behavior.