CheckTx cleanup

[pompon0]

• removed sender field from ResponseCheckTx - it is never set, never used and ResponseCheckTx is never persisted.
• removed unused results of runTx and grouped the remaining ones into a struct.

[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	Apr 30, 2026, 11:25 AM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.21%. Comparing base (08689b2) to head (0f5af37).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3347      +/-   ##
==========================================
- Coverage   59.21%   59.21%   -0.01%     
==========================================
  Files        2097     2097              
  Lines      172509   172489      -20     
==========================================
- Hits       102152   102133      -19     
+ Misses      61501    61500       -1     
  Partials     8856     8856              

Flag	Coverage Δ
sei-chain-pr	67.07% <100.00%> (?)
sei-db	70.41% <ø> (ø)

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

Files with missing lines	Coverage Δ
sei-cosmos/baseapp/abci.go	61.92% <100.00%> (+0.13%)	⬆️
sei-cosmos/baseapp/baseapp.go	76.42% <100.00%> (-0.10%)	⬇️
sei-cosmos/baseapp/test_helpers.go	66.66% <100.00%> (ø)
sei-tendermint/internal/mempool/mempool.go	72.23% <ø> (-0.55%)	⬇️
sei-tendermint/internal/mempool/tx.go	76.28% <ø> (-0.56%)	⬇️

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