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

web/src/pages/Explorer.tsx

@@ -1,7 +1,7 @@
 import React, { useState, useEffect, useCallback } from 'react';
 import { useNavigate } from 'react-router-dom';
 import Layout from '@/components/Layout';
-import { usePolkadot } from '@/contexts/PolkadotContext';
+import { usePezkuwi } from '@/contexts/PezkuwiContext';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -64,7 +64,7 @@ interface NetworkStats {
 
 const Explorer: React.FC = () => {
   const navigate = useNavigate();
-  const { api, isApiReady } = usePolkadot();
+  const { api, isApiReady } = usePezkuwi();
 
   const [stats, setStats] = useState<NetworkStats>({
     bestBlock: 0,