fix: Comprehensive authentication and UI fixes

Authentication & Token Management:
- Add deviceId to token refresh flow (backend requires both refreshToken and deviceId)
- Fix React Strict Mode token clearing race condition with retry logic
- Improve AuthContext to handle all token state combinations properly
- Store deviceId in localStorage alongside tokens

UI/UX Improvements:
- Remove deprecated legacyBehavior from Next.js Link components
- Update primary theme color to WCAG AA compliant #7c3aed
- Fix nested button error in TabBar voice navigation
- Fix invalid Tabs value error in DynamicChildDashboard

Multi-Child Dashboard:
- Load all children into Redux store properly
- Fetch metrics for all children, not just selected one
- Remove mock data to prevent unauthorized API calls

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

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

maternal-web/styles/themes/purpleTheme.ts

@@ -6,9 +6,10 @@ import { createTheme } from '@mui/material/styles';
 export const purpleTheme = createTheme({
   palette: {
     primary: {
-      main: '#8b52ff', // Vibrant purple
-      light: '#d194e6', // Light purple
-      dark: '#6b3cc9', // Dark purple
+      main: '#7c3aed', // Adjusted purple for better contrast (WCAG AA compliant)
+      light: '#a78bfa', // Light purple
+      dark: '#5b21b6', // Dark purple
+      contrastText: '#ffffff', // Ensure white text
     },
     secondary: {
       main: '#ff7094', // Pink