Upgrade to Go v1.25.6

[masih]

Upgrade the go module, workspace and reflect the changes across CI and
containers.

Fixes PLT-80

[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	Jan 16, 2026, 12:49 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.77%. Comparing base (1fed545) to head (ccb9dbc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2713      +/-   ##
==========================================
+ Coverage   43.76%   43.77%   +0.01%     
==========================================
  Files        1913     1913              
  Lines      159491   159491              
==========================================
+ Hits        69794    69817      +23     
+ Misses      83275    83260      -15     
+ Partials     6422     6414       -8     

Flag	Coverage Δ
sei-chain	45.77% <ø> (+<0.01%)	⬆️
sei-cosmos	38.20% <ø> (ø)
sei-db	68.72% <ø> (ø)
sei-tendermint	47.33% <ø> (+0.05%)	⬆️

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see 16 files with indirect coverage changes

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