fix(quality): Ruff/CVE/TS-Fixes, 104 neue Tests, Complexity-Refactoring

- Ruff: 144 auto-fixes (unused imports, == None → is None), F821/F811/F841 manuell
- CVEs: python-multipart>=0.0.22, weasyprint>=68.0, pillow>=12.1.1, npm audit fix (0 vulns)
- TS: 5 tote Drafting-Engine-Dateien entfernt, allowed-facts/sanitizer/StepHeader/context fixes
- Tests: +104 (ISMS 58, Evidence 18, VVT 14, Generation 14) → 1449 passed
- Refactoring: collect_ci_evidence (F→A), row_to_response (E→A), extract_requirements (E→A)
- Dead Code: pca-platform, 7 Go-Handler, dsr_api.py, duplicate Schemas entfernt

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-compliance/compliance/services/seeder.py

@@ -5,8 +5,7 @@ Seeds the database with initial regulations, controls, and requirements.
 """
 
 import logging
-from typing import Dict, List, Optional
-from datetime import datetime
+from typing import Dict
 
 from sqlalchemy.orm import Session
 
@@ -23,7 +22,6 @@ from ..db.models import (
     ControlTypeEnum,
     ControlDomainEnum,
     ControlStatusEnum,
-    RiskLevelEnum,
     ServiceTypeEnum,
     RelevanceLevelEnum,
 )