feat(artillery, auto-topup): implement auto top-up functionality for ledger balance

test command:
```
NETWORK=naga-staging bun run artillery:init --auto-topu
```

Author: Ansonhkg

e2e/artillery/src/init.ts

@@ -1,20 +1,71 @@
-import '../../src/helper/supressLogs';
 import {
   createAuthManager,
   storagePlugins,
   ViemAccountAuthenticator,
 } from '@lit-protocol/auth';
-import * as StateManager from './StateManager';
 import { createLitClient } from '@lit-protocol/lit-client';
-import { getOrCreatePkp } from '../../../e2e/src/helper/pkp-utils';
 import * as NetworkManager from '../../../e2e/src/helper/NetworkManager';
+import { getOrCreatePkp } from '../../../e2e/src/helper/pkp-utils';
+import '../../src/helper/supressLogs';
 import * as AccountManager from '../src/AccountManager';
+import * as StateManager from './StateManager';
 
 const _network = process.env['NETWORK'];
 
+const AUTO_TOP_UP_FLAG = '--auto-topup';
+const args = process.argv.slice(2);
+
 // CONFIGURATIONS
 const REJECT_BALANCE_THRESHOLD = 0;
 const LEDGER_MINIMUM_BALANCE = 10000;
+const AUTO_TOP_UP_ENABLED = args.includes(AUTO_TOP_UP_FLAG);
+const AUTO_TOP_UP_INTERVAL = 10_000;
+const AUTO_TOP_UP_THRESHOLD = LEDGER_MINIMUM_BALANCE;
+
+if (Number.isNaN(LEDGER_MINIMUM_BALANCE) || LEDGER_MINIMUM_BALANCE < 0) {
+  throw new Error('❌ LEDGER_MINIMUM_BALANCE must be a non-negative number');
+}
+
+const ensureLedgerThreshold = async ({
+  paymentManager,
+  accountAddress,
+  minimumBalance,
+}: {
+  paymentManager: Awaited<
+    ReturnType<typeof AccountManager.getAccountDetails>
+  >['paymentManager'];
+  accountAddress: `0x${string}`;
+  minimumBalance: number;
+}) => {
+  const { availableBalance } = await paymentManager.getBalance({
+    userAddress: accountAddress,
+  });
+
+  const currentAvailable = Number(availableBalance);
+
+  if (currentAvailable >= minimumBalance) {
+    return currentAvailable;
+  }
+
+  const diff = minimumBalance - currentAvailable;
+
+  console.log(
+    `🚨 Live Master Account Ledger Balance (${currentAvailable}) is below threshold (${minimumBalance}). Depositing ${difference} ETH.`
+  );
+
+  await paymentManager.deposit({
+    amountInEth: diff.toString(),
+  });
+
+  const { availableBalance: postTopUpBalance } =
+    await paymentManager.getBalance({
+      userAddress: accountAddress,
+    });
+
+  console.log('✅ New Live Master Account Payment Balance:', postTopUpBalance);
+
+  return Number(postTopUpBalance);
+};
 
 (async () => {
   // -- Start
@@ -43,32 +94,11 @@ const LEDGER_MINIMUM_BALANCE = 10000;
     );
   }
 
-  if (LEDGER_MINIMUM_BALANCE > Number(masterAccountDetails.ledgerBalance)) {
-    // find the difference between the minimum balance and the current balance
-    const difference =
-      LEDGER_MINIMUM_BALANCE - Number(masterAccountDetails.ledgerBalance);
-
-    console.log(
-      `🚨 Live Master Account Ledger Balance is less than LEDGER_MINIMUM_BALANCE: ${LEDGER_MINIMUM_BALANCE} ETH. Attempting to top up the difference of ${difference} ETH to the master account.`
-    );
-
-    // deposit the difference
-    console.log(
-      '\x1b[90m✅ Depositing the difference to Live Master Account Payment Manager...\x1b[0m'
-    );
-    await masterAccountDetails.paymentManager.deposit({
-      amountInEth: difference.toString(),
-    });
-
-    // print the new balance
-    const newBalance = await masterAccountDetails.paymentManager.getBalance({
-      userAddress: masterAccount.address,
-    });
-    console.log(
-      '✅ New Live Master Account Payment Balance:',
-      newBalance.availableBalance
-    );
-  }
+  await ensureLedgerThreshold({
+    paymentManager: masterAccountDetails.paymentManager,
+    accountAddress: masterAccount.address,
+    minimumBalance: LEDGER_MINIMUM_BALANCE,
+  });
 
   // 3. Authenticate the master account and store the auth data
   const masterAccountAuthData = await StateManager.getOrUpdate(
@@ -145,5 +175,38 @@ const LEDGER_MINIMUM_BALANCE = 10000;
 
   // console.log('✅ PKP Sign Test Result:', res);
 
-  process.exit();
+  if (AUTO_TOP_UP_ENABLED) {
+    console.log(
+      `\n✅ Auto top-up enabled. Monitoring every ${AUTO_TOP_UP_INTERVAL}ms with threshold ${AUTO_TOP_UP_THRESHOLD} ETH. Press Ctrl+C to exit.`
+    );
+
+    let isTopUpInProgress = false;
+
+    const poll = async () => {
+      if (isTopUpInProgress) {
+        return;
+      }
+
+      isTopUpInProgress = true;
+
+      try {
+        await ensureLedgerThreshold({
+          paymentManager: masterAccountDetails.paymentManager,
+          accountAddress: masterAccount.address,
+          minimumBalance: AUTO_TOP_UP_THRESHOLD,
+        });
+      } catch (error) {
+        console.error('❌ Auto top-up check failed:', error);
+      } finally {
+        isTopUpInProgress = false;
+      }
+    };
+
+    await poll();
+    setInterval(() => {
+      void poll();
+    }, AUTO_TOP_UP_INTERVAL);
+  } else {
+    process.exit();
+  }
 })();