fix(statics): migrate xtzevm testnet from deprecated shadownet to ghostnet

Update XtzEvmTestnet network config to point to the new Etherlink ghostnet
testnet (testnet.explorer.etherlink.com) from the deprecated shadownet.
Chain ID remains 128123.

Fixes: CECHO-864

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TICKET: CECHO-864

Author: manojkumar138

modules/sdk-core/src/bitgo/environments.ts

@@ -513,7 +513,7 @@ const testnetBase: EnvironmentTemplate = {
       apiToken: process.env.ETHERSCAN_API_TOKEN,
     },
     xtzevm: {
-      baseUrl: 'https://shadownet.explorer.etherlink.com/api',
+      baseUrl: 'https://testnet.explorer.etherlink.com/api',
     },
     flow: {
       baseUrl: 'https://evm-testnet.flowscan.io',

modules/statics/src/networks.ts

@@ -741,8 +741,8 @@ class XtzEvm extends Mainnet implements EthereumNetwork {
 class XtzEvmTestnet extends Testnet implements EthereumNetwork {
   name = 'Testnet XTZ EVM';
   family = CoinFamily.XTZEVM;
-  explorerUrl = 'https://shadownet.explorer.etherlink.com/tx/';
-  accountExplorerUrl = 'https://shadownet.explorer.etherlink.com/address/';
+  explorerUrl = 'https://testnet.explorer.etherlink.com/tx/';
+  accountExplorerUrl = 'https://testnet.explorer.etherlink.com/address/';
   chainId = 128123;
   nativeCoinOperationHashPrefix = '128123';
 }