feat(pages): add A/B testing framework for landing pages

Implement comprehensive A/B testing system for landing page optimization:
- Database models for experiments, variants, and events
- AI-powered variant generation and analysis
- Visitor tracking with conversion metrics
- Experiment lifecycle management (draft/active/paused/completed)
- Email notifications for experiment results
- Cron job for automated experiment monitoring
- UI for viewing experiment results and statistics

options/locale/locale_en-US.json

@@ -4493,6 +4493,15 @@
   "repo.settings.pages.seo_description": "Meta Description",
   "repo.settings.pages.seo_keywords": "Keywords",
   "repo.settings.pages.og_image": "Open Graph Image URL",
+  "repo.settings.pages.brand_favicon_url": "Favicon URL",
+  "repo.settings.pages.brand_favicon_url_help": "URL to a custom favicon for your landing page (ICO, PNG, or SVG). Leave blank to use the default.",
+  "repo.settings.pages.navigation": "Navigation Links",
+  "repo.settings.pages.navigation_desc": "Control which built-in links appear in the header and footer navigation.",
+  "repo.settings.pages.nav_show_docs": "Show Docs link (links to wiki)",
+  "repo.settings.pages.nav_show_api": "Show API link (links to Swagger docs)",
+  "repo.settings.pages.nav_show_repository": "Show Repository link (View Source button)",
+  "repo.settings.pages.nav_show_releases": "Show Releases link",
+  "repo.settings.pages.nav_show_issues": "Show Issues link",
   "repo.vault": "Vault",
   "repo.vault.secrets": "Secrets",
   "repo.vault.new_secret": "New Secret",