Fix all shadow deprecation warnings across entire mobile app

- Replaced shadowColor/shadowOffset/shadowOpacity/shadowRadius with boxShadow
- Fixed 28 files (21 screens + 7 components)
- Preserved elevation for Android compatibility
- All React Native Web deprecation warnings resolved

Files fixed:
- All screen components
- All reusable components
- Navigation components
- Modal components

mobile/src/screens/__tests__/WalletScreen.test.tsx

@@ -1,7 +1,7 @@
 import React from 'react';
 import { render } from '@testing-library/react-native';
 import { LanguageProvider } from '../../contexts/LanguageContext';
-import { PolkadotProvider } from '../../contexts/PolkadotContext';
+import { PezkuwiProvider } from '../contexts/PezkuwiContext';
 import WalletScreen from '../WalletScreen';
 
 jest.mock('@react-navigation/native', () => ({
@@ -11,9 +11,9 @@ jest.mock('@react-navigation/native', () => ({
 
 const WalletScreenWrapper = () => (
   <LanguageProvider>
-    <PolkadotProvider>
+    <PezkuwiProvider>
       <WalletScreen />
-    </PolkadotProvider>
+    </PezkuwiProvider>
   </LanguageProvider>
 );