Update UI_UPDATE.MD: Mark 3.3.3 Mobile Navigation task as completed

UI_UPDATE.MD

@@ -352,10 +352,12 @@ Always come back and update UI_UPDATE.MD once complete with task and task item.
 
 **Notes:** Implemented comprehensive touch interaction enhancements for mobile devices. The 44px minimum touch targets were already in place using var(--min-tap-target-size, 44px) in components.css. Added swipe gesture support on video area for chat toggling (swipe left to hide, right to show chat on mobile). Implemented pull-to-refresh functionality that triggers refresh when pulling down from top of page on mobile. Added double-tap gesture on video area to toggle fullscreen. All touch interactions are mobile-only to avoid conflicts on desktop.
 
-#### 3.3.3: Mobile Navigation
-- [ ] Create bottom navigation pattern
-- [ ] Implement mobile chat controls
-- [ ] Add mobile-specific UI toggles
+#### 3.3.3: Mobile Navigation - COMPLETED 9/29/2025
+- [x] Create bottom navigation pattern
+- [x] Implement mobile chat controls
+- [x] Add mobile-specific UI toggles
+
+**Notes:** Implemented comprehensive mobile bottom navigation bar with essential controls. Added fixed bottom navigation with 4 main buttons (Chat, Refresh, Fullscreen, PiP) that appears only on mobile devices (max-width: 767px). Navigation includes proper touch targets (44px minimum), Dodgers-themed styling with gradient background, and accessibility features. Integrated with existing mobile touch gestures and maintains compatibility with swipe controls. Added safe area support for devices with notches. Bottom navigation provides easy access to core functionality without obscuring video content.
 
 ### Sub-task 3.4: Tablet and Desktop Optimizations