Flatten sei-tendermint go mod into sei-chain

[masih]

Flatten the sei-tendermint go module into sei-chain tin reduce dependency management complexity and error-prone multi layer replace directives.

Part of PLT-6

[github-actions]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 6, 2026, 12:43 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.88%. Comparing base (5c26262) to head (521fa5e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2817      +/-   ##
==========================================
+ Coverage   56.58%   56.88%   +0.30%     
==========================================
  Files        2033     2050      +17     
  Lines      166263   168332    +2069     
==========================================
+ Hits        94074    95764    +1690     
- Misses      63926    64156     +230     
- Partials     8263     8412     +149     

Flag	Coverage Δ
sei-chain	52.24% <ø> (+10.73%)	⬆️
sei-cosmos	48.13% <ø> (ø)
sei-db	68.72% <ø> (ø)
sei-tendermint	?

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Files with missing lines	Coverage Δ
app/abci.go	66.92% <ø> (ø)
app/ante/cosmos_checktx.go	36.14% <ø> (+0.54%)	⬆️
app/ante/evm_checktx.go	33.75% <ø> (ø)
app/app.go	66.14% <ø> (ø)
app/apptesting/test_suite.go	24.44% <ø> (ø)
app/benchmark.go	44.82% <ø> (ø)
app/benchmark/benchmark.go	60.00% <ø> (ø)
app/benchmark/generator.go	46.04% <ø> (ø)
app/benchmark/logger.go	92.92% <ø> (ø)
app/eth_replay.go	0.00% <ø> (ø)
... and 137 more

... and 50 files with indirect coverage changes

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