feat(wallet): Production-ready wallet with real blockchain integration

Wallet Features:
- Fix address encoding (48 byte → 32 byte) for chain queries
- Add gas fee preview before sending transactions
- Add address validation with error display
- Add real-time balance via chain subscription
- Add address book (save/load frequently used addresses)
- Add balance check before send (insufficient funds warning)
- Use transferKeepAlive to prevent account reaping

UI/UX:
- Browser title: "Pezkuwi Wallet" → "Pezkuwi"
- Update favicon from shared/images
- Standardize token logos (hez_token_512.png, pez_token_512.png)

Infrastructure:
- Fix zombienet endpoint: wss://beta-rpc.pezkuwichain.io:19944
- Disable indexer API (not production ready yet)
- Optimize logo images for mobile (5MB → 300KB)

mobile/src/contexts/PezkuwiContext.tsx

@@ -86,7 +86,7 @@ export const NETWORKS: Record<NetworkType, NetworkConfig> = {
   zombienet: {
     name: 'zombienet',
     displayName: 'Zombienet Dev (Alice/Bob)',
-    rpcEndpoint: 'wss://zombienet-rpc.pezkuwichain.io',
+    rpcEndpoint: 'wss://beta-rpc.pezkuwichain.io:19944',
     ss58Format: 42,
     type: 'dev',
   },