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 18, 2026, 3:50 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 57.31%. Comparing base (2a1ccca) to head (39b8c23).
⚠️ Report is 1 commits behind head on main.

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   57.33%   57.31%   -0.02%     
==========================================
  Files        2089     2089              
  Lines      172126   172181      +55     
==========================================
+ Hits        98683    98687       +4     
- Misses      64646    64691      +45     
- Partials     8797     8803       +6     

Flag	Coverage Δ
sei-chain	52.79% <33.33%> (-0.02%)	⬇️
sei-cosmos	48.19% <ø> (ø)
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 25 files with indirect coverage changes

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[arajasek]

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