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/tests/test_dsfa_routes.py

@@ -429,7 +429,7 @@ class TestGetTenantId:
         assert _get_tenant_id("my-tenant") == "my-tenant"
 
     def test_default_constant_value(self):
-        assert DEFAULT_TENANT_ID == "default"
+        assert DEFAULT_TENANT_ID == "9282a473-5c95-4b3a-bf78-0ecc0ec71d3e"
 
 
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