feat: Google Consent Mode v2 + Developer Portal cookie banner docs

Phase A: Google Consent Mode v2 in cookie-banner-embed.ts
- gtag('consent', 'default', {...denied}) before banner loads
- gtag('consent', 'update', {...}) after user decision
- Automatic mapping: statistics→analytics_storage, marketing→ad_storage

Phase B: 5 Developer Portal pages at /sdk/consent/cookie-banner/
- Overview page with 4 cards
- Integration Guide: 3-step setup, script-tag, categories
- Google Consent Mode: automatic integration, parameter mapping
- Script Blocking: type=text/plain pattern, GA/FB/Hotjar examples
- Compliance Checklist: 12 points, 9 automatic

Sidebar navigation extended with Cookie-Banner section.

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

developer-portal/components/SDKDocsSidebar.tsx

@@ -52,6 +52,17 @@ const navigation: NavItem[] = [
       { title: 'Flutter', href: '/sdk/consent/mobile/flutter' },
     ],
   },
+  {
+    title: 'Cookie-Banner',
+    href: '/sdk/consent/cookie-banner',
+    icon: <Shield className="w-4 h-4" />,
+    children: [
+      { title: 'Integration Guide', href: '/sdk/consent/cookie-banner/integration' },
+      { title: 'Google Consent Mode', href: '/sdk/consent/cookie-banner/google-consent-mode' },
+      { title: 'Script Blocking', href: '/sdk/consent/cookie-banner/script-blocking' },
+      { title: 'Compliance Checklist', href: '/sdk/consent/cookie-banner/checklist' },
+    ],
+  },
   {
     title: 'Sicherheit',
     href: '/sdk/consent/security',