feat: Add comprehensive accessibility improvements and medical tracking

- **EULA Persistence Fix**: Fixed EULA dialog showing on every login
  - Added eulaAcceptedAt/eulaVersion to AuthResponse interface
  - Updated login/register/getUserById endpoints to return EULA fields
  - Changed EULACheck to use refreshUser() instead of window.reload()

- **Touch Target Accessibility**: All interactive elements now meet 48x48px minimum
  - Fixed 14 undersized IconButtons across 5 files
  - Changed size="small" to size="medium" with minWidth/minHeight constraints
  - Updated children page, AI chat, analytics cards, legal viewer

- **Alt Text for Images**: Complete image accessibility for screen readers
  - Added photoAlt field to children table (Migration V009)
  - PhotoUpload component now includes alt text input field
  - All Avatar components have meaningful alt text
  - Default alt text: "Photo of {childName}", "{userName}'s profile photo"

- **Medical Tracking Consolidation**: Unified medical page with tabs
  - Medicine page now has 3 tabs: Medication, Temperature, Doctor Visit
  - Backward compatibility for legacy 'medicine' activity type
  - Created dedicated /track/growth page for physical measurements

- **Track Page Updates**:
  - Simplified to 6 options: Feeding, Sleep, Diaper, Medical, Activity, Growth
  - Fixed grid layout to 3 cards per row with minWidth: 200px
  - Updated terminology from "Medicine" to "Medical"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

maternal-web/components/layouts/MobileNav/MobileNav.tsx

@@ -73,7 +73,7 @@ export const MobileNav = () => {
           >
             <Home />
           </IconButton>
-          <Avatar sx={{ bgcolor: 'primary.main' }}>U</Avatar>
+          <Avatar sx={{ bgcolor: 'primary.main' }} alt="User profile photo">U</Avatar>
         </Toolbar>
       </AppBar>
 
@@ -89,7 +89,7 @@ export const MobileNav = () => {
           aria-label="Main menu"
         >
           <Box sx={{ p: 3, bgcolor: 'primary.light' }}>
-            <Avatar sx={{ width: 64, height: 64, bgcolor: 'primary.main', mb: 2 }}>U</Avatar>
+            <Avatar sx={{ width: 64, height: 64, bgcolor: 'primary.main', mb: 2 }} alt="User profile photo">U</Avatar>
             <Typography variant="h6" fontWeight="600">User Name</Typography>
             <Typography variant="body2" color="text.secondary">user@example.com</Typography>
           </Box>