fix(harness): stabilize compaction-after-waiting user-state race proof

[dennisonbertram]

Problem

Hosted race CI on combined #1129 failed TestCompactRunWhileWaitingForUserPreservesCompactionAfterResume: expected waiting_for_user, got running. The failure is outside native stack diff and blocks a green baseline.

Acceptance criteria

• Determine production status/event defect vs fixture timing.
• Add deterministic normal/race proof of waiting-for-user before compaction/resume.
• Preserve runner/broker ordering, compaction, pending input, resume, persistence/API/TUI semantics.
• Sol medium diagnosis, isolated issue PR, cheap re-review, full regression/hosted green.

Scope

Harness runner waiting-state test/implementation as evidence warrants. Blocks stack promotion due red baseline.

[dennisonbertram]

Pre-implementation contract: fresh worktree is aligned to origin/main 7df20f3. Search establishes Runner.Subscribe history/live stream plus EventRunWaitingForUser as the public readiness boundary; PendingInput can intentionally precede it. Plan and cross-surface map: docs/plans/2026-08-03-issue-1132-compaction-fixture-{plan,impact-map}.md. Test-only scope: subscribe immediately after StartRun and await that event before pending/status assertions, preserving all compaction/resume/event-order/output assertions. Expected red is the hosted race fixture observation of running before public waiting publication. Planned proof: focused normal/race x100, full harness normal/race, full regression; no production changes.