`precheckBalance` should also verify token allowance, not just balance

## `precheckBalance` should also verify token allowance, not just balance

### Problem
The current `precheckBalance` only checks the token balance but ignores allowance, causing validation to pass but execution to fail.

**Current code:**

```solidity
if (paymasterData.precheckBalance) {
uint256 balance = SafeTransferLib.balanceOf(paymasterData.token, userOp.sender);
if (balance < maxTokenCost) {
revert SenderTokenBalanceTooLow(paymasterData.token, balance, maxTokenCost);
}
}
```

**Issue**

UserOperations pass validation even when:

- Sender hasn't approved the paymaster
- Allowance is less than maxTokenCost

This creates false positives - operations appear valid but fail during bundling.

**Proposed Solution**

Check both balance and allowance:

```solidity
if (paymasterData.precheckBalance) {
uint256 balance = SafeTransferLib.balanceOf(paymasterData.token, userOp.sender);
uint256 allowance = SafeTransferLib.allowance(paymasterData.token, userOp.sender, address(this));
uint256 available = balance < allowance ? balance : allowance;

if (available < maxTokenCost) {
revert SenderInsufficientTokensOrAllowance(paymasterData.token, balance, allowance, maxTokenCost);
}
}
```

This improves validation accuracy and reduces bundling failures.