fix: Implement Associated Token Account for USDC withdrawals

- Fixed PublicKey undefined error (derive from DRIFT_WALLET_PRIVATE_KEY)
- Implemented ATA resolution using @solana/spl-token
- Added comprehensive debug logging for withdrawal flow
- Fixed AccountOwnedByWrongProgram error (need ATA not wallet address)
- Successfully tested .58 withdrawal with on-chain confirmation
- Updated .env with TOTAL_WITHDRAWN and LAST_WITHDRAWAL_TIME tracking

Key changes:
- lib/drift/withdraw.ts: Added getAssociatedTokenAddress() for USDC ATA
- tsconfig.json: Excluded archive folders from compilation
- package.json: Added bn.js as direct dependency

Transaction: 4drNfMR1xBosGCQtfJ2a4r6oEawUByrT6L7Thyqu6QQWz555hX3QshFuJqiLZreL7KrheSgTdCEqMcXP26fi54JF
Wallet: 3dG7wayp7b9NBMo92D2qL2sy1curSC4TTmskFpaGDrtA
USDC ATA: 8ZEMwErnwxPNNNHJigUcMfrkBG14LCREDdKbqKm49YY7

package-lock.json

@@ -14,6 +14,7 @@
         "@pythnetwork/price-service-client": "^1.3.0",
         "@solana/web3.js": "^1.91.1",
         "autoprefixer": "^10.4.21",
+        "bn.js": "^5.2.2",
         "bs58": "^5.0.0",
         "next": "^15.0.0",
         "postcss": "^8.5.6",