feat: token balances hook, network hook, mismatch banner, and auto-reconnect

[boys-cyberhub]

Closes #22
Closes #23
Closes #24
Closes #25

Summary

• #22 — Implement useTokenBalances hook (SAC tokens) #22 useTokenBalances — features/wallet/hooks/useTokenBalances.ts: React Query hook fetching USDC/BTC/ETH/XLM balances from Horizon /accounts/{address} (trustlines + native XLM). Returns Record<string, number>, staleTime/refetchInterval 15 s, only enabled when wallet is connected. Balance row wired into the TradePanel collateral input header.
• #23 — Implement useNetwork hook #23 useNetwork — features/wallet/hooks/useNetwork.ts: Returns { network, isTestnet, isMainnet, mismatch } from the wallet store. mismatch is true when the wallet is connected and the stored network differs from VITE_NETWORK.
• #24 — Network mismatch warning banner #24 NetworkMismatchBanner — features/wallet/components/NetworkMismatchBanner.tsx: Top-of-page role="alert" banner rendered when mismatch && connected. Skipped on the landing page (/). Dismissible for the session via sessionStorage.
• #25 — Auto-reconnect on page refresh #25 Auto-reconnect — features/wallet/components/WalletProvider.tsx: On mount, if the store has a persisted address+walletId, calls walletKit.setWallet(walletId) then walletKit.getAddress(). Matching address → setConnected; mismatch or any error → setDisconnected silently (no toast). Mounted in __root.tsx wrapping all routes.

Test plan

• Connect a wallet, refresh the page — verify no connection modal appears and the app shows the connected address
• Remove the wallet extension, refresh — verify the store clears and no error toast fires
• Set VITE_NETWORK=testnet with a mainnet wallet connected — verify the yellow banner appears on /trade but not on /
• Dismiss the banner — verify it disappears for the session and reappears after reconnecting
• Confirm the "Balance:" row appears next to the Collateral label when wallet is connected
• Disconnect wallet — verify Balance row disappears

[drips-wave]

@boys-cyberhub Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits