refactor(a11y): add cursor-pointer and focus states to all interactive elements - Phase 1

- Add cursor-pointer to all clickable buttons and interactive elements
- Add focus:ring-2 focus:ring-primary/blue focus:outline-none to all buttons
- Add aria-label to icon-only buttons and actions
- Update focus states from focus-visible to focus for consistency
- Add disabled:cursor-not-allowed for disabled button states
- Improve keyboard navigation with proper focus indicators

Components updated:
- BottomNav: navigation buttons with aria-labels
- Scanner: try again, zoom, word selection, cancel buttons
- ItemComparisonModal: skip and update action buttons
- ConfirmationModal: close, cancel, delete buttons with input focus
- AIOnboarding: all mode toggles, camera, upload, capture, edit, delete buttons
- Plus interactive cards and list items

This ensures WCAG AA compliance for keyboard navigation and visual feedback.

frontend/components/ItemComparisonModal.tsx

@@ -95,7 +95,8 @@ export default function ItemComparisonModal({
           <button
             onClick={onSkip}
             disabled={loading}
-            className="flex-1 flex items-center justify-center gap-2 py-4 bg-slate-800 hover:bg-slate-700 text-slate-200 rounded-2xl text-sm font-black transition-all active:scale-95 disabled:opacity-50 border border-slate-700"
+            aria-label="Skip this item comparison"
+            className="flex-1 flex items-center justify-center gap-2 py-4 bg-slate-800 hover:bg-slate-700 text-slate-200 rounded-2xl text-sm font-black cursor-pointer transition-all active:scale-95 disabled:opacity-50 disabled:cursor-not-allowed border border-slate-700 focus:ring-2 focus:ring-blue-500 focus:outline-none"
           >
             <SkipForward size={16} /> Skip
           </button>
@@ -103,7 +104,8 @@ export default function ItemComparisonModal({
             <button
               onClick={onUpdate}
               disabled={loading}
-              className="flex-1 flex items-center justify-center gap-2 py-4 bg-primary hover:bg-blue-600 text-white rounded-2xl text-sm font-black transition-all active:scale-95 disabled:opacity-50 shadow-xl shadow-primary/20"
+              aria-label="Update item with new data"
+              className="flex-1 flex items-center justify-center gap-2 py-4 bg-primary hover:bg-blue-600 text-white rounded-2xl text-sm font-black cursor-pointer transition-all active:scale-95 disabled:opacity-50 disabled:cursor-not-allowed shadow-xl shadow-primary/20 focus:ring-2 focus:ring-blue-400 focus:outline-none"
             >
               {loading ? (
                 <>