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/api/legal_template_routes.py

@@ -314,9 +314,9 @@ async def update_legal_template(
         raise HTTPException(status_code=400, detail="No fields to update")
 
     if "document_type" in updates and updates["document_type"] not in VALID_DOCUMENT_TYPES:
-        raise HTTPException(status_code=400, detail=f"Invalid document_type")
+        raise HTTPException(status_code=400, detail="Invalid document_type")
     if "status" in updates and updates["status"] not in VALID_STATUSES:
-        raise HTTPException(status_code=400, detail=f"Invalid status")
+        raise HTTPException(status_code=400, detail="Invalid status")
 
     set_clauses = ["updated_at = :updated_at"]
     params: Dict[str, Any] = {