fix(ci): repair Bun 1.4.2 regression coverage and Senpi bundle

[code-yeongyu]

Summary

Repair the red dev CI introduced by the Bun 1.4.2 integration and restore the committed Senpi bundle generated on Linux.

Root cause

• Run 34307575373 exposed the failures.
• Merge commit 131fa3e96 from PR chore: upgrade Bun types to 1.4.2 #7971 incorrectly reintroduced planRuntimePrune and selectPruneEntries imports and duplicate describe blocks into script/build-omob.test.ts after PR fix(omob): never prune a dev runtime a live process still executes #7994 (73f0ddd14) extracted the implementation and tests to script/omob-runtime-prune.ts / script/omob-runtime-prune.test.ts.
• The committed Senpi extension artifacts were stale relative to a fresh Linux build after the Bun 1.4.2 bump and merged changes.

Changes

• Remove only the duplicate prune imports and describe blocks from script/build-omob.test.ts; retain the intentional Windows portability changes from chore: upgrade Bun types to 1.4.2 #7971.
• Regenerate the three changed committed Senpi extension bundles on Linux with Bun 1.4.2. The complete CI Senpi build pipeline was run and no other tracked generated artifact was stale.

Verification

• On gorky (linux/x86_64) with Bun 1.4.2: bun run typecheck:script passed.
• On gorky: bun test script/build-omob.test.ts script/omob-runtime-prune.test.ts passed, 26 tests, 59 expectations, 0 failures.
• The pre-build build-extension.mjs --check reported stale-output; the post-build check reported omo-senpi extension build is current.
• Bundle bytes were transferred with bunshin readBytes; local SHA-256 matched the remote Linux rebuild for all three artifacts. Detailed evidence is in .omo/evidence/20260909-dev-ci-fix/README.md.
• The ci:full-matrix label is applied to require Ubuntu, macOS, and Windows coverage.

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Summary by cubic

Repairs the red dev CI by removing duplicate runtime-prune tests reintroduced in a merge and regenerating stale Senpi extension bundles on Linux with Bun 1.4.2.

• Removes only the duplicated planRuntimePrune/selectPruneEntries imports and describe blocks from script/build-omob.test.ts; the intentional Windows portability changes from chore: upgrade Bun types to 1.4.2 #7971 stay.
• Regenerates the three committed Senpi extension bundles (omo-member.js, omo-task.js, omo.js) so they match a fresh Linux build.

^{Written for commit c6e56f9. Summary will update on new commits.}