fix(async-jobs): stop await-tool timers from hanging tests

[mastertyko]

TL;DR

What: Stops await_tool integration hangs by making completed-job eviction timers non-blocking and shutting test managers down explicitly.
Why: The async-jobs test lane could keep late-suite processes alive, which blocked honest local verification for multiple otherwise-correct fixes.
How: Unref the eviction timer in AsyncJobManager and add explicit manager teardown/assertions in the await-tool tests.

What

This change updates the shared async-jobs blocker used by the current verification round. It keeps completed-job eviction timers from holding the Node process open and tightens the await-tool tests so each test shuts its manager down explicitly.

Affected areas:

• src/resources/extensions/async-jobs/job-manager.ts
• src/resources/extensions/async-jobs/await-tool.test.ts

Why

This fixes a real late-suite hang in the await_tool integration family. Without it, unrelated issue branches could go green on targeted checks and still fail to finish the full local CI mirror honestly because the async-jobs test process stayed alive.

How

AsyncJobManager.scheduleEviction() now unref()s its timer when available, so completed-job eviction does not keep the process alive. The await-tool tests now also shut down their managers explicitly and assert the completed-job timer is unref'd.

Change type

• fix — Bug fix
• feat — New feature or capability
• refactor — Code restructuring (no behavior change)
• test — Adding or updating tests
• docs — Documentation only
• chore — Build, CI, or tooling changes

Scope

• pi-tui — Terminal UI
• pi-ai — AI/LLM layer
• pi-agent-core — Agent orchestration
• pi-coding-agent — Coding agent
• gsd extension — GSD workflow
• native — Native bindings
• ci/build — Workflows, scripts, config

Breaking changes

• No breaking changes
• Yes — described above

Test plan

• CI passes
• New/updated tests included
• Manual testing — steps described above
• No tests needed — explained above

Verified locally with the full CI mirror gate:

• npm run build
• npm run typecheck:extensions
• npm run test:unit
• npm run test:integration

The final truth phase was re-run in a plain verification clone on the exact branch head after the worktree signal showed a late verifier-environment stall.

AI disclosure

• This PR includes AI-assisted code — prepared with Codex and verified as described in the test plan above.

[github-actions]

🟡 PR Risk Report — MEDIUM

Files changed	2
Systems affected	1
Overall risk	🟡 MEDIUM

Affected Systems

Risk	System
🟡 medium	Async Jobs

File Breakdown

Risk	File	Systems
🟡	src/resources/extensions/async-jobs/job-manager.ts	Async Jobs
⚪	src/resources/extensions/async-jobs/await-tool.test.ts	(unclassified)