Extract findPatternMatchesIn*Files() to ProjectFileAssertionSupport
trait for reuse. Add contract tests for:
- GR-SEC-005: Encryption centralized in Crypto.php
- GR-SEC-006: File storage in storage/, not web/
- GR-SEC-002: No PII in error_log() calls
- GR-CORE-012: POST-Redirect-GET pattern enforcement
- GR-UI-015: i18n key completeness de ↔ en
Brings automated guard coverage from 24 to 29 test files.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
