#745 land: undo-wait-test-budget

Accepted agent delivery; branch-keyed search descriptor included.

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Summary by cubic

Refactors the undo-against-held-namespace test helper to accept a plain Duration instead of a pre-built bounded-IO Budget, and adds a search slice descriptor for the undo-wait test budget.

• Callers now pass a Duration; the helper converts it to a Budget internally.
• Adds land-undo-wait-test-budget.json, a non-ranking harness slice that targets the harness-goldens fixtures.

Confidence Score: 5/5

This PR appears safe to merge.

Summary

Starts the undo test’s request budget after fixture setup, just before measuring the restore call.

• Undo wait tests start their request budget after the fixture is ready.

_{Reviews (1) · Last reviewed commit: "release notes and search-quality descrip..." · Reviewed by Greptile}