fix(evmrpc): return empty array instead of null for eth_getFilterLogs and eth_getFilterChanges

[amir-deris]

Summary

eth_getFilterLogs and eth_getFilterChanges were returning null instead of [] when no logs matched — violating the Ethereum JSON-RPC spec, which requires these methods to always return an array.

• Return []*ethtypes.Log{} instead of nil in GetFilterLogs and GetFilterChanges for all no-result paths (exhausted bounded filters, no matching logs, empty range queries)
• Export NewFilterMethod and GetFilterLogsMethod constants to replace magic strings in tests
• Add tests asserting the empty-array contract for both methods

[github-actions]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 21, 2026, 6:43 PM

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.36%. Comparing base (f2f5f21) to head (393c2ff).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
evmrpc/filter.go	25.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3292   +/-   ##
=======================================
  Coverage   59.36%   59.36%           
=======================================
  Files        2072     2072           
  Lines      169942   169947    +5     
=======================================
+ Hits       100887   100892    +5     
  Misses      60271    60271           
  Partials     8784     8784           

Flag	Coverage Δ
sei-chain-pr	64.43% <25.00%> (?)
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
evmrpc/filter.go	69.89% <25.00%> (+0.22%)	⬆️

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