Add reusable styles and helpers to shared package:
- Coverage styles (high/med/low) with FormatCoverage() helper
- Priority styles (high/medium/low) with FormatPriority() helper
- Severity styles (critical/high/medium/low) with FormatSeverity() helper
Update packages to use shared styles:
- cmd/test: use shared coverage styles and FormatCoverage()
- cmd/php: use shared status, QA, and severity styles
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>