fix(ui): keep task context menu open

[Phoenix500526]

Summary

Delay opening a task's context menu until the secondary-button release and
its native default action have completed. This prevents Chromium's popover
light-dismiss behavior from immediately closing the menu on macOS while
preserving keyboard and post-release context-menu invocation.

Fixes #4983

Verification

• node --test packages/ui/dist/__tests__/session-history-multi-select.test.js
  — 22 passed, including a regression test that fails before the fix
• npx biome check packages/ui/src/session-history-list.tsx packages/ui/src/__tests__/session-history-multi-select.test.tsx
  — passed
• npm --workspace @maka/core run build and
  npm --workspace @maka/ui run build — passed
• Manual Electron verification on macOS — the task menu remains open after
  the secondary button is released
• npm test — all reported assertions passed, but the parallel workspace
  runner returned code 1 once for MCP and once for CLI; isolated reruns passed
  186/186 and 861/861 respectively

AI use

Select exactly one:

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

Tool(s) and scope: Codex diagnosed the pointer-event ordering, implemented
the focused fix and regression test, and ran verification. The commit includes
the required Generated-by: Codex trailer.

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

[Astro-Han]

Thanks for the focused fix. Reviewed caed2e6; no blocking findings. Verified the production component in Chromium for deferred opening, post-release and keyboard invocation, and cancellation, with no page errors. These checks dispatch DOM events; native macOS gesture verification is reported in the PR. CI is green. Review assisted by Codex.