fix(giga): write receipt for state-transition errors that bump the nonce (CON-256)

[wen-coding]

Invariant

A receipt is written for an EVM tx iff that tx bumped the sender's nonce. Equivalently: any tx the chain treats as having advanced the sender's account state — and only those — is observable via eth_getTransactionByHash / eth_getTransactionReceipt. Txs included in a block but rejected before the nonce bump (e.g. ante-handler failures, pre-execution state-transition errors) leave no receipt and are invisible to standard EVM clients, matching go-ethereum semantics.

This PR fixes a place where the Giga executor violated the invariant: a state-transition error inside Execute() (notably EIP-7623 floor-data-gas underflow, post-Pectra) bumped the sender's nonce but produced no receipt, so eth_getTransactionReceipt returned null forever and clients that polled for it hung. The invariant is now enforced symmetrically across V2 and Giga.

How the invariant is enforced

V2 path (no change in this PR — already correct):

1. BasicDecorator.AnteHandle registers a WithDeliverTxCallback (x/evm/ante/basic.go:33-39) that fires after DeliverTx regardless of success/failure. The callback bumps the sender's nonce and calls SetNonceBumped.
2. After msgServer.EVMTransaction returns err, the SDK populates ExecTxResult.Code != 0 and ExecTxResult.Log = err.Error().
3. At EndBlock, GetAllEVMTxDeferredInfo (x/evm/keeper/deferred.go:24) synthesizes a DeferredInfo{TxHash, Error: txRes.Log} for each tx that didn't append its own.
4. The EndBlock loop (x/evm/keeper/abci.go:100-113) writes a synthetic receipt for entries with Error != "" — gated on GetNonceBumped, which is exactly the invariant. Existing coverage: TestEndBlock_NoReceiptForNonceMismatch and TestEndBlock_ReceiptCreatedWhenNonceBumped in x/evm/keeper/abci_test.go.

Giga path (fixed in this PR):

1. executeEVMTxWithGigaExecutor already explicitly bumps the sender's nonce in its execErr != nil branch (app/app.go:1887).
2. It also calls AppendToEvmTxDeferredInfo for surplus tracking — but with Error == "", so the EndBlock synthetic-receipt loop above skips it.
3. Fix: call WriteReceipt directly in the err-branch, gated on the explicit nonce bump it already does. EIP-1559 effective gas price is used (not GasFeeCap) so the receipt's EffectiveGasPrice matches go-ethereum semantics for dynamic-fee txs.

Tests

• TestGiga_FailedExecution_ProducesReceipt (giga/tests/giga_test.go) drives the EIP-7623 floor-data-gas-underflow case through the Giga executor, asserts the explicit nonce bump (nonceBefore+1 == nonceAfter) to lock in the invariant, and asserts the receipt was written with status=0, gasUsed=gasLimit, and the floor-data-gas error in VmError.

Things done

• Giga path (app/app.go): write receipt in execErr != nil branch using EIP-1559 effective gas price
• Giga test: nonce-bump assertion + receipt assertion
• gofmt -s clean

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	May 6, 2026, 4:40 PM

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.08%. Comparing base (7004ef1) to head (2ffebc5).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
app/app.go	66.66%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3383   +/-   ##
=======================================
  Coverage   59.08%   59.08%           
=======================================
  Files        2100     2099    -1     
  Lines      173008   173019   +11     
=======================================
+ Hits       102222   102235   +13     
+ Misses      61922    61920    -2     
  Partials     8864     8864           

Flag	Coverage Δ
sei-chain-pr	59.08% <66.66%> (?)
sei-db	70.41% <ø> (ø)

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Files with missing lines	Coverage Δ
app/app.go	70.46% <66.66%> (+0.60%)	⬆️

... and 31 files with indirect coverage changes

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