fix(giga): correct synchronous executor mode

[arajasek]

Describe your changes and provide context

Incorporate the iterator fallback introduced in #3560 to giga's synchronous mode.

Testing performed to validate your change

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PR Summary

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Jun 10, 2026, 7:09 PM

[codecov]

Codecov Report

❌ Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.33%. Comparing base (b29c2ab) to head (0dadc5b).

Files with missing lines	Patch %	Lines
app/app.go	0.00%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3573      +/-   ##
==========================================
- Coverage   59.18%   58.33%   -0.86%     
==========================================
  Files        2210     2136      -74     
  Lines      183259   174723    -8536     
==========================================
- Hits       108470   101931    -6539     
+ Misses      64992    63701    -1291     
+ Partials     9797     9091     -706     

Flag	Coverage Δ
sei-chain-pr	49.97% <0.00%> (?)
sei-db	70.41% <ø> (ø)
sei-db-state-db	?

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Files with missing lines	Coverage Δ
app/app.go	70.57% <0.00%> (-0.47%)	⬇️

... and 74 files with indirect coverage changes

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