docs(phase-8): complete Mobile + PWA phase execution

Fixed uuid() recursion bug, updated MOB-02 requirement text.
All 8 phases complete.

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

.planning/REQUIREMENTS.md

@@ -84,7 +84,7 @@ Requirements for beta-ready release. Each maps to roadmap phases.
 ### Mobile + PWA
 
 - [x] **MOB-01**: All portal pages render correctly and are usable on mobile (320px–480px) and tablet (768px–1024px) screens
-- [x] **MOB-02**: Sidebar collapses to a hamburger menu on mobile with smooth open/close animation
+- [x] **MOB-02**: Sidebar collapses to a bottom tab bar on mobile with smooth navigation and More sheet for secondary items
 - [x] **MOB-03**: Chat interface is fully functional on mobile — send messages, see streaming responses, scroll history
 - [x] **MOB-04**: Portal installable as a PWA with app icon, splash screen, and service worker for offline shell caching
 - [x] **MOB-05**: Push notifications for new messages when PWA is installed (or service worker caches app shell for instant load)