[giga] add mixed mode integration test and fixes for app hash

[stevenlanders]

Giga Executor: Fix AppHash Divergence & Add Mixed-Mode Integration Tests

For failed executor txs, Giga was missing:
Nonce increment — V2 bumps it even on failure
Finalize() — commits the fee SubBalance to store
Surplus tracking — tells EndBlock to credit EVM module account
GasWanted field — included in LastResultsHash computation

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 10, 2026, 6:36 PM

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.77%. Comparing base (ff992dd) to head (a78876f).

Files with missing lines	Patch %	Lines
app/app.go	46.15%	13 Missing and 1 partial ⚠️
giga/executor/executor.go	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2831       +/-   ##
===========================================
+ Coverage   46.23%   56.77%   +10.53%     
===========================================
  Files        2005     2070       +65     
  Lines      163000   168308     +5308     
===========================================
+ Hits        75366    95557    +20191     
+ Misses      81111    64263    -16848     
- Partials     6523     8488     +1965     

Flag	Coverage Δ
sei-chain	40.85% <50.00%> (-0.01%)	⬇️
sei-cosmos	48.13% <ø> (ø)
sei-db	68.72% <ø> (ø)
sei-tendermint	58.73% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
giga/executor/executor.go	32.00% <66.66%> (-10.11%)	⬇️
app/app.go	65.79% <46.15%> (-0.06%)	⬇️

... and 356 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.