feat(desktop): offer safe resume after user stop

[me2seeks]

Summary

Offer the existing Continue this turn action directly on the Desktop status
notice produced by the renderer Stop button.

Desktop now treats an aborted Turn as an explicit resume candidate only when
its abort source is renderer.stop_button. Other cancellation sources remain
ineligible for this presentation path.

The button reuses the existing Desktop resume controller and
sessions:resumeLatest IPC operation. It does not pre-authorize continuation:
the Runtime Host planner still decides whether the stopped Run is safe and
returns the existing refusal reasons when it is not.

This PR is stacked on the explicit-resume policy PR.

Closes #5205

Verification

• npm run rebuild
• npm --workspace @maka/ui run test:dist
• npm --workspace @maka/desktop run test:dist
  • Desktop: 2494 passed, 0 failed
• Focused Desktop selector and UI interaction coverage: 22 passed, 0 failed
• npm run check:renderer-architecture -- --base cb3af4b2f24a3ace8d9574ca60396ffc1cc97219
  • architecture fixtures: 103 passed, 0 failed
• npm run lint
• npm run format:check
• npm run check:asf-headers
• npm run check:stale
• git diff --check

A packaged Desktop visual smoke test was not run. The button visibility and
click behavior are covered by the DOM interaction regression; the final
placement still needs human UX review.

Hosted CI has not run yet.

Review focus

Please verify that the Stop outcome is the correct place for this action and
that matching renderer.stop_button is sufficiently narrow. The Runtime Host,
rather than the renderer selector, must remain the safety authority.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: OpenAI Codex traced the Desktop Stop projection and existing
resume controller, implemented the affordance and regressions, updated the
architecture documentation, and performed adversarial pre-PR review.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No