fix(giga): three fixes for v2-matching correctness

[arajasek]

Describe your changes and provide context

Three commits:

• port fixes to test branch port fixes to test branch #2834
• fix(giga): perform initial fee validation: ported from Enable stStackTests, stCreate2, stCreateTest state tests #2782, with lint fixed
• fix(giga): increase nonce even in early-exit case: fixes the apphash mismatch caused by this transaction

Testing performed to validate your change

[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 13, 2026, 6:22 PM

[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 13, 2026, 3:26 PM

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.15%. Comparing base (7407960) to head (add8a7d).

Files with missing lines	Patch %	Lines
app/app.go	29.62%	32 Missing and 6 partials ⚠️
giga/executor/executor.go	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2889       +/-   ##
===========================================
+ Coverage   48.34%   57.15%    +8.80%     
===========================================
  Files         671     2091     +1420     
  Lines       50615   171579   +120964     
===========================================
+ Hits        24471    98063    +73592     
- Misses      24002    64762    +40760     
- Partials     2142     8754     +6612     

Flag	Coverage Δ
sei-chain	52.62% <33.33%> (?)
sei-cosmos	48.16% <ø> (+<0.01%)	⬆️
sei-db	68.72% <ø> (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%> (ø)
app/app.go	71.02% <29.62%> (ø)

... and 1542 files with indirect coverage changes

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[arajasek]

Update: dropped the port of #2832 since it needs further discussion.