fix: add merged to finished state

[thomasrockhu-codecov]

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Note

Low Risk
Low risk, small change limited to an idempotency guard in the upload finisher. Main risk is incorrectly skipping work if merged is reached before all required finisher steps in some edge case.

Overview
Updates UploadFinisherTask's idempotency check to consider the merged upload state as a final/terminal state (alongside processed and error). This allows repeated/duplicated finisher invocations to short-circuit when uploads have already been merged, reducing redundant processing.

^{Written by Cursor Bugbot for commit 5928de2. This will update automatically on new commits. Configure here.}

[sentry]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.27%. Comparing base (138b687) to head (5928de2).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #770   +/-   ##
=======================================
  Coverage   92.27%   92.27%           
=======================================
  Files        1305     1305           
  Lines       47938    47938           
  Branches     1628     1628           
=======================================
  Hits        44233    44233           
  Misses       3396     3396           
  Partials      309      309           

Flag	Coverage Δ
workerintegration	58.56% <ø> (ø)
workerunit	90.40% <ø> (ø)

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[codecov-notifications]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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