feat(research): reduce canonical run events safely

[CompleteDotTech]

Summary

• add a client-safe reducer for canonical opencoven.run-event/v1 frames
• buffer out-of-order events and deterministically drain contiguous prefixes
• make identical replay idempotent and fail closed on same-sequence conflicts, malformed frames, and wrong-run frames
• project lifecycle status, phases, activity, evidence, failure, and retention updates
• register focused reducer coverage in the repository runner

Bead

• cave-8o5s7.1

Verification

• focused reducer suite — 7 passed
• pnpm lint
• pnpm typecheck
• pnpm check:tests-wired — 1978/1978
• git diff --check

Rebased from current origin/main before publication.