Add Upcoming Features page with timeline-based roadmap

New Page: /upcoming
- Created comprehensive Upcoming Features page with 3 timeline phases
- Phase 1 (Feb 2026): Linker Module, Optimizer Module
- Phase 2 (Q2 2026): Products Pages, Services Pages, Company Pages
- Phase 3 (Q3-Q4 2026): Socializer, Video Creator, Site Builder, Analytics

Features:
- Timeline-based organization with unique color badges
- Rich visual design with gradients and hover effects
- Detailed feature descriptions with bullet points
- Icons for each module
- CTA sections for conversion

Integration:
- Added route to MarketingApp.tsx
- Added 'Upcoming Features' link to footer Resources section
- Updated FINAL-PRELAUNCH.md to mark task 8.3 complete

All upcoming features from docs integrated:
- Internal/external linking with clustering
- Content re-optimization
- Product/service/company page generation
- Social media multi-platform publishing
- Video content creation and publishing
- Site builder (SEO holy grail)
- Advanced analytics

frontend/src/marketing/data/navLinks.ts

@@ -36,6 +36,7 @@ export const footerNavGroups: { title: string; links: NavLinkItem[] }[] = [
       { name: "Help Center", path: "/resources#help" },
       { name: "Documentation", path: "/resources#docs" },
       { name: "Partner Program", path: "/partners" },
+      { name: "Upcoming Features", path: "/upcoming" },
     ],
   },
 ];