parquet v2 refactor reader worker pool

[jewei1997]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	May 5, 2026, 1:16 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.18%. Comparing base (52e76c6) to head (e741244).

Additional details and impacted files

@@                             Coverage Diff                             @@
##           parquet-refactor-v2-coordinator-thread2    #3348      +/-   ##
===========================================================================
- Coverage                                    59.29%   59.18%   -0.11%     
===========================================================================
  Files                                         2107     2097      -10     
  Lines                                       173714   172515    -1199     
===========================================================================
- Hits                                        103002   102105     -897     
+ Misses                                       61738    61558     -180     
+ Partials                                      8974     8852     -122     

Flag	Coverage Δ
sei-chain-pr	?
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
sei-db/ledger_db/parquet/store.go	69.68% <ø> (ø)

... and 12 files with indirect coverage changes

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