fix: cancel active turns during session shutdown

[7Sageer]

Related Issue

No linked issue. This fixes a prompt-mode shutdown regression where foreground Bash processes could outlive kimi -p when the CLI receives SIGTERM or SIGHUP.

Problem

Prompt-mode signal cleanup closed the harness, but session shutdown only stopped managed background tasks. If a foreground Bash tool was still running, the active turn was not canceled during Session.close(), so the Bash tool never received the abort signal it uses to terminate the child process. Managed background Bash timeout timers also remained referenced, which could keep kimi -p alive after the prompt completed.

What changed

• Cancel active turns during Session.close() before background-task shutdown, with a bounded wait and timeout warning.
• unref() managed background Bash timeout timers so they do not keep prompt mode alive.
• Handle SIGHUP in prompt-mode termination cleanup, matching standard signal exit code 129.
• Add unit coverage for active turn cancellation and prompt-mode SIGTERM/SIGHUP cleanup.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 3a069a4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@moonshot-ai/agent-core	Patch
@moonshot-ai/kimi-code	Patch

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[pkg-pr-new]

pnpm dlx https://pkg.pr.new/@moonshot-ai/kimi-code@3a069a4

npx https://pkg.pr.new/@moonshot-ai/kimi-code@3a069a4

commit: 3a069a4