test(safety): add comprehensive tests for safety framework modules

Add tests to improve backend coverage from 85% to 93%:

- test_audit.py: 60 tests for AuditLogger (20% -> 99%)
  - Hash chain integrity, sanitization, retention, handlers
  - Fixed bug: hash chain modification after event creation
  - Fixed bug: verification not using correct prev_hash

- test_hitl.py: Tests for HITL manager (0% -> 100%)
- test_permissions.py: Tests for permissions manager (0% -> 99%)
- test_rollback.py: Tests for rollback manager (0% -> 100%)
- test_metrics.py: Tests for metrics collector (0% -> 100%)
- test_mcp_integration.py: Tests for MCP safety wrapper (0% -> 100%)
- test_validation.py: Additional cache and edge case tests (76% -> 100%)
- test_scoring.py: Lock cleanup and edge case tests (78% -> 91%)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/context/adapters/claude.py

@@ -123,7 +123,9 @@ class ClaudeAdapter(ModelAdapter):
             if score:
                 # Escape score to prevent XML injection via metadata
                 escaped_score = self._escape_xml(str(score))
-                parts.append(f'<document source="{source}" relevance="{escaped_score}">')
+                parts.append(
+                    f'<document source="{source}" relevance="{escaped_score}">'
+                )
             else:
                 parts.append(f'<document source="{source}">')