Update test vectors to match current implementation

## Description

The current test vectors need to be updated to match the current implementation. There's a commented out test case that needs to be updated with correct expected values.

## Current TODO Comment

```zig
// TODO: Update test vectors to match current implementation
// .{
// .input_state = [_]F.FieldElem{42} ** 16,
// .output_state = .{ 834546835, 1886829340, 1792314086, 1487871337, 567666274, 1133976664, 445360408, 630502830, 161668903, 153566288, 448274346, 619034796, 1156499614, 1851146900, 777523375, 393617892 },
// },
```

## Tasks

- [ ] Run the current implementation with the input state `[42] ** 16`
- [ ] Capture the actual output state
- [ ] Update the test vector with the correct expected output
- [ ] Verify the test passes with the updated values
- [ ] Ensure all other test vectors are still valid

## Priority

Medium - This affects test coverage and validation of the implementation.

## Labels

- enhancement
- testing
- poseidon2