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 17, 2026, 2:29 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 57.23%. Comparing base (8fc1d5b) to head (a7a7753).

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   57.21%   57.23%   +0.01%     
==========================================
  Files        2093     2093              
  Lines      171755   171787      +32     
==========================================
+ Hits        98276    98321      +45     
+ Misses      64709    64694      -15     
- Partials     8770     8772       +2     

Flag	Coverage Δ
sei-chain	52.70% <33.33%> (+<0.01%)	⬆️
sei-cosmos	48.18% <ø> (+0.03%)	⬆️
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%> (-10.11%)	⬇️
app/app.go	71.10% <29.62%> (-1.65%)	⬇️

... and 31 files with indirect coverage changes

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[arajasek]

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