feat: add AskUserQuestion runtime and TUI

[Astro-Han]

Summary

• Add one shared turn-scoped await primitive and the AskUserQuestion runtime request/response contract.
• Register the AI SDK tool only for the root TUI surface and render a FIFO terminal interaction with bounded options, Other input, explicit unanswered answers, and Stop support.
• Preserve answers only as the normal JSON tool result so the same model turn can continue without fabricating a user turn.

Why

Refs #825. Agents need a bounded way to ask the user for missing decisions and then continue the same turn. This extends the existing permission/runtime/TUI seams while keeping their separate policy and lifecycle responsibilities.

Scope

Desktop registration and UI remain PR3. This PR deliberately excludes maka run, headless/Harbor, Pi transport, child agents, and the other out-of-scope items recorded in #825.

Verification

• npm --workspace @maka/core test — 873 passed, 0 failed.
• npm --workspace @maka/runtime test — 1,470 passed, 0 failed, 7 skipped.
• npm --workspace maka-agent test — 317 passed, 0 failed.
• npm run typecheck — all workspaces passed.
• git diff --check origin/main...HEAD — passed.
• Interactive behavior is covered with the real pi-tui FakeTerminal: bottom-overlay rendering and placement, FIFO sequencing, keyboard selection, Other editing/submission, Esc unanswered, Stop, abort, and late responses. A static screenshot is not useful evidence for this stateful terminal interaction.

Impact

The root interactive TUI gains AskUserQuestion. Existing permission behavior remains unchanged, including its 300-second timeout; user questions have no fixed timeout and remain interruptible by Stop/abort/teardown. No migration or release-note action is required.

Reviewer notes

The response command is intentionally ephemeral. Only the resulting JSON tool result is durable. Reviewer completed two full-diff passes, including after rebasing onto current main, with no P0–P3 findings and a Go conclusion.

Ready for review

• Verification is complete and the results above are current
• Impact, compatibility, migration, documentation, and release-note needs are addressed
• User-visible UI/UX changes include visual evidence, or Verification explains why it is not applicable