Fix USDT swap insufficient balance bug

Root cause: Token symbol mismatch between TokenSwap component and WalletContext
- WalletContext stored balance with key 'USDT'
- TokenSwap used symbol 'wUSDT' for lookups
- This caused balances['wUSDT'] to return undefined
- Triggered false "insufficient balance" errors

Changes:
- Updated TokenSwap.tsx to use 'USDT' symbol consistently
- Fixed token symbol in AVAILABLE_TOKENS array
- Updated asset ID mapping in swap transaction logic
- Fixed swap history token display

Also includes:
- Added new DEX components (SwapInterface, PoolBrowser, etc.)
- Added TypeScript type definitions for DEX
- Added DEX utility functions
- Removed obsolete test scripts
- Updated WalletContext with USDT balance support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

tsconfig.json

@@ -7,7 +7,8 @@
   "compilerOptions": {
     "baseUrl": ".",
     "paths": {
-      "@/*": ["./src/*"]
+      "@/*": ["./src/*"],
+      "@pezkuwi/i18n": ["../shared/i18n"]
     },
     "noImplicitAny": false,
     "noUnusedParameters": false,