feat: A/B Testing + Compliance Report PDF (F5 + F8)

F5: A/B Testing for Consent Rate
- Migration 116: banner_variants table + variant tracking in audit log
- BannerABService: deterministic sticky bucketing via device hash,
  chi-squared significance testing, variant CRUD
- banner_ab_routes: 6 endpoints (CRUD + stats + assign)
- ABTestPanel.tsx: variant creation, traffic sliders, opt-in comparison
  chart with winner/significance badges
- New "A/B-Test" tab in cookie-banner page

F8: Compliance Report PDF
- CompliancePDFGenerator: reportlab-based A4 PDF covering all modules
  (Company Profile, TOM, VVT, DSFA, Risks, Vendors, Incidents,
  Reviews, Consents, Roles)
- compliance_report_routes: GET /compliance/report/pdf
- "Compliance-Report herunterladen" button on SDK dashboard

[migration-approved]

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-compliance/app/sdk/cookie-banner/page.tsx

@@ -10,8 +10,9 @@ import { VendorTable } from './_components/VendorTable'
 import { EmbeddableVendorHTML } from './_components/EmbeddableVendorHTML'
 import { SiteSelector } from './_components/SiteSelector'
 import { AnalyticsDashboard } from './_components/AnalyticsDashboard'
+import { ABTestPanel } from './_components/ABTestPanel'
 
-type BannerTab = 'config' | 'vendors' | 'embed' | 'analytics'
+type BannerTab = 'config' | 'vendors' | 'embed' | 'analytics' | 'abtest'
 
 export default function CookieBannerPage() {
   const { state } = useSDK()
@@ -77,6 +78,7 @@ export default function CookieBannerPage() {
           { id: 'vendors' as const, label: 'Verarbeiter' },
           { id: 'embed' as const, label: 'Einbettung' },
           { id: 'analytics' as const, label: 'Analytik' },
+          { id: 'abtest' as const, label: 'A/B-Test' },
         ]).map(tab => (
           <button key={tab.id} onClick={() => setActiveTab(tab.id)}
             className={`px-4 py-3 text-sm font-medium border-b-2 -mb-px transition-colors ${
@@ -96,6 +98,9 @@ export default function CookieBannerPage() {
       {/* Tab: Analytik */}
       {activeTab === 'analytics' && <AnalyticsDashboard siteId={activeSiteId || undefined} />}
 
+      {/* Tab: A/B-Test */}
+      {activeTab === 'abtest' && <ABTestPanel siteConfigId={activeSiteId || undefined} />}
+
       {/* Tab: Konfiguration */}
       {activeTab !== 'config' ? null : (<>
       {/* Stats */}