fix(giga): bail on wrong nonce as v2 does (#2963)

## Describe your changes and provide context

Reopening #2877 against main

fixes mismatch of [this block](https://seiscan.io/txs?block=193119398).
there are 2 txs (don't show up on seiscan) that have invalid nonces:
```
V2's log: "nonce too high: address 0x6a9dE37D180C56b7E9362d7688ACa8B7acEb425C, tx: 23213 state: 23211"

V2's log: "nonce too high: address 0x4A7d9e41340d1dba4d157fdE37Ed1697E42CBC7b, tx: 7423188 state: 7423187"
```

In this case we just bail WITHOUT bumping the nonce.

## Testing performed to validate your change

tests pass, get us past the block in question.

Author: arajasek

app/app.go

@@ -1746,6 +1746,24 @@ func (app *App) executeEVMTxWithGigaExecutor(ctx sdk.Context, msg *evmtypes.MsgE
 
 	_, isAssociated := app.GigaEvmKeeper.GetEVMAddress(ctx, seiAddr)
 
+	// ============================================================================
+	// Nonce validation (mirrors V2's ante handler check in x/evm/ante/sig.go)
+	// V2 rejects with ErrWrongSequence if txNonce != expectedNonce, with NO state changes.
+	// ============================================================================
+	expectedNonce := app.GigaEvmKeeper.GetNonce(ctx, sender)
+	txNonce := ethTx.Nonce()
+	if txNonce != expectedNonce {
+		nonceDirection := "too high"
+		if txNonce < expectedNonce {
+			nonceDirection = "too low"
+		}
+		return &abci.ExecTxResult{
+			Code:      sdkerrors.ErrWrongSequence.ABCICode(),
+			GasWanted: int64(ethTx.Gas()), //nolint:gosec
+			Log:       fmt.Sprintf("nonce %s: address %s, tx: %d state: %d: %s", nonceDirection, sender.Hex(), txNonce, expectedNonce, sdkerrors.ErrWrongSequence.Error()),
+		}, nil
+	}
+
 	// ============================================================================
 	// Fee validation (mirrors V2's ante handler checks in evm_checktx.go)
 	// NOTE: In V2, failed transactions still increment nonce and charge gas.