fix(freigabe): Vorbereitung-Module release prep — Python 3.9 fix, Scope Engine tests, MkDocs

- fix: company_profile_routes.py — dict|None → Optional[dict] for Python 3.9 compat (9/9 tests grün)
- test: 40 Vitest-Tests für ComplianceScopeEngine (calculateScores, determineLevel,
  evaluateHardTriggers, evaluate integration, buildDocumentScope, evaluateRiskFlags)
- docs: vorbereitung-module.md — Profil, Scope, UCCA vollständig dokumentiert
- docs: mkdocs.yml — Nav-Eintrag "Vorbereitung-Module (Paket 1)" vor Analyse-Module

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

backend-compliance/compliance/api/company_profile_routes.py

@@ -139,7 +139,7 @@ def row_to_response(row) -> CompanyProfileResponse:
     )
 
 
-def log_audit(db, tenant_id: str, action: str, changed_fields: dict | None, changed_by: str | None):
+def log_audit(db, tenant_id: str, action: str, changed_fields: Optional[dict], changed_by: Optional[str]):
     """Write an audit log entry."""
     try:
         db.execute(