emit rewards withdrawn events for delegate

[codchen]

Describe your changes and provide context

When a delegator delegates more tokens to a validator that they've already delegated to, their rewards with that validator will be withdrawn automatically. We want this withdrawal to be accompanied by an event when delegation/redelegation happens through the staking precompile.

Testing performed to validate your change

unit test

[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 11, 2026, 7:16 AM

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.77%. Comparing base (ff992dd) to head (faaea59).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
precompiles/staking/staking.go	66.66%	3 Missing and 4 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2828       +/-   ##
===========================================
+ Coverage   46.23%   56.77%   +10.53%     
===========================================
  Files        2005     2070       +65     
  Lines      163000   168299     +5299     
===========================================
+ Hits        75366    95547    +20181     
+ Misses      81111    64252    -16859     
- Partials     6523     8500     +1977     

Flag	Coverage Δ
sei-chain	40.86% <66.66%> (+0.01%)	⬆️
sei-cosmos	48.12% <ø> (-0.01%)	⬇️
sei-db	68.72% <ø> (ø)
sei-tendermint	58.73% <ø> (?)

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

Files with missing lines	Coverage Δ
precompiles/staking/staking.go	77.30% <66.66%> (-0.27%)	⬇️

... and 354 files with indirect coverage changes

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