perf(evm): cache repeated balance lookups

[codchen]

Summary

• cache spendable EVM balances within an execution request so repeated EXTCODEHASH calls for no-code addresses avoid repeated bank, vesting, and auth account work
• scope cached entries to the active multistore layer and invalidate them at bank and auth write choke points
• preserve behavior across snapshots, reverts, copies, tracer resets, nested StateDBs, and the Giga implementation

Testing

• go test ./x/evm/state ./x/evm/keeper ./giga/deps/xevm/state ./giga/deps/xevm/keeper ./sei-cosmos/x/auth/keeper ./sei-cosmos/x/bank/keeper ./giga/deps/xbank/keeper
• go test -race ./x/evm/state ./giga/deps/xevm/state -run Test(GetCodeHashCachesBalanceForNoCodeAddress|BalanceCache) -count=1
• go test ./sei-cosmos/types
• gofmt -d and goimports -d on all touched Go files
• git diff --check

make fmtcheck could not reach source checks locally because golangci-lint v2.8.0 reported that its Go 1.24.5 build cannot analyze this module targeting Go 1.25.6.

[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	Aug 24, 2026, 2:21 AM

[codecov]

Codecov Report

❌ Patch coverage is 86.41975% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.89%. Comparing base (73f917b) to head (c2604af).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
giga/deps/xevm/state/statedb.go	50.00%	6 Missing ⚠️
x/evm/state/statedb.go	66.66%	4 Missing ⚠️
giga/deps/xbank/keeper/send.go	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3986      +/-   ##
==========================================
- Coverage   58.98%   57.89%   -1.09%     
==========================================
  Files        2310     2212      -98     
  Lines      197500   185998   -11502     
==========================================
- Hits       116487   107683    -8804     
+ Misses      70256    68497    -1759     
+ Partials    10757     9818     -939     

Flag	Coverage Δ
sei-chain-pr	77.63% <86.41%> (?)
sei-db	69.80% <ø> (ø)
sei-db-state-db	?

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

Files with missing lines	Coverage Δ
giga/deps/xevm/keeper/balance.go	100.00% <100.00%> (ø)
sei-cosmos/types/context.go	90.94% <100.00%> (+0.06%)	⬆️
sei-cosmos/types/evm_balance_cache.go	100.00% <100.00%> (ø)
sei-cosmos/x/auth/keeper/account.go	69.56% <100.00%> (+1.38%)	⬆️
sei-cosmos/x/bank/keeper/send.go	91.45% <100.00%> (+0.12%)	⬆️
x/evm/keeper/balance.go	100.00% <100.00%> (ø)
giga/deps/xbank/keeper/send.go	84.61% <75.00%> (-0.15%)	⬇️
x/evm/state/statedb.go	78.83% <66.66%> (-0.94%)	⬇️
giga/deps/xevm/state/statedb.go	61.57% <50.00%> (-1.00%)	⬇️

... and 99 files with indirect coverage changes

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