refactor(arch): split userWalletsHandler.js into 7 modular files (#52)

- 747-line monolith → 8 files (all ≤108 lines)
- balanceHandler (96 lines): showBalance, handleBackToBalance
- historyHandler (107 lines): handleTransactionHistory, handleWalletHistory
- refreshHandler (75 lines): handleRefreshBalance with balance refresh
- createHandler (94 lines): handleAddWallet, handleGenerateWallet
- topUpHandler (60 lines): handleTopUpWallet
- archiveHandler (86 lines): handleViewArchivedWallets
- helpers (19 lines): getNetworkName, getWalletAddress
- index.js (20 lines): re-exports all 11 handler methods
- Removed duplicate getBaseWalletType (now uses WalletUtils)
- Removed duplicate getNetworkName (now in helpers.js)

src/index.js

@@ -9,7 +9,7 @@ import userHandler from "./handlers/userHandlers/userHandler.js";
 import userPurchaseHandler from "./handlers/userHandlers/userPurchaseHandler.js";
 import userLocationHandler from "./handlers/userHandlers/userLocationHandler.js";
 import userProductHandler from "./handlers/userHandlers/userProductHandler.js";
-import userWalletsHandler from "./handlers/userHandlers/userWalletsHandler.js";
+import userWalletsHandler from "./handlers/userHandlers/wallet/index.js";
 import userDeletionHandler from "./handlers/userHandlers/userDeletionHandler.js";
 import adminHandler from "./handlers/adminHandlers/adminHandler.js";
 import adminUserLocationHandler from "./handlers/adminHandlers/adminUserLocationHandler.js";