[ghzhost]

Summary

Closes #49

Enforces strict asset issuer verification when deriving balances in useWallet, BalanceCard, and WalletInfo:

• xlmBalance verifies asset.code === 'XLM' && asset.issuer === null, preventing any custom/spoofed token called "XLM" from shadowing native lumens.
• usdcBalance verifies asset.code === 'USDC' && asset.issuer === expectedUsdcIssuer matching the pinned USDC_TESTNET or USDC_MAINNET issuer based on the active network.
• BalanceCard and WalletInfo custom asset lists accurately exclude only native XLM and official USDC, cleanly surfacing any third-party or custom tokens.

Testing

• Added comprehensive unit tests in src/hooks/useWallet.test.tsx checking native XLM priority, network-specific USDC verification, and spoofed asset resilience.
• Ran test suite with 100% passing results (28 test files, 116 tests).