fix(ask-user): restore the wait countdown and tighten the question card layout

[bobleer]

Summary

• The AskUserQuestion card lost its whole wait-timing affordance in two ordinary
  states. The header only rendered the countdown when the host reported a finite
  deadline that had not been acknowledged yet, so a card with the question timeout
  disabled (host reports responseDeadlineMs: null) or an already-acknowledged
  card showed an empty right slot with no countdown and no xmark.
• Wait timing now belongs to the AskUser design-system contract (waitTiming).
  While a host deadline runs the header shows the m:ss countdown plus its
  dismiss control; when no deadline governs the answer it shows a settled
  No time limit label. An acknowledged interaction still clears the slot, which
  keeps the existing "click the countdown or its xmark to settle the wait" behavior.
• Option copy in the FlowChat card is stacked instead of split: the description
  sat right-aligned in a capped column, which left a wide hole between the label
  and its description and a ragged right edge. Labels now sit above a left-aligned
  description, and the row's vertical padding follows the content.
• Fixed the dead space between the last option and the footer. A 1fr grid row in
  an auto-height grid inflated the expanded card by ~76px past its content. Only
  the collapsing summary transitions its row and carries the shrinking min-size
  now, so the collapse animation stays and the expanded card measures its content.

Validation

• design-system/packages/ui: vite build + vite build --config vite.mobile.config.ts + tsc -p tsconfig.build.json — passed
• node --test design-system/packages/ui/tests/*.test.mjs — passed (343 tests, includes the new waitTiming contract test)
• node --test design-system/apps/design-lab/vite/component-detail-contract.test.mjs — passed (34 tests)
• src/web-ui: npx vitest run src/flow_chat/tool-cards/AskUserQuestionCard.test.tsx — passed (41 tests, adds unbounded-wait and acknowledged-wait assertions)
• packages/flow-chat-presentation: tsc -p tsconfig.json --noEmit — passed
• tsc -p src/web-ui/tsconfig.json --noEmit — passed
• node scripts/i18n-audit.mjs — passed with 0 warnings
• node scripts/audit-frontend-colors.mjs — passed (all 26 surfaces)
• node scripts/validate-theme-visual-contract.mjs — passed
• node scripts/verify-webkit-compatibility.cjs — passed
• Rendered the built component with the token/theme/component CSS in a browser and
  measured the card: the header shows 2:31 ✕ and No time limit, options stack
  with no dead space, and the completed card is 76px shorter than before.

Pre-existing failures in this checkout, reproduced identically with both commits
reverted, so they are not regressions from this PR:

• src/web-ui: full vitest run reports 248 failing tests across 23 files with
  and without this change (environmental, e.g. localStorage unavailable here).
• packages/flow-chat-presentation: tests/catalog.test.tsx fails on existing
  tool-catalog drift (AgentDelete/Task/AgentControl) with and without this
  change.

Remote scenarios

• Remote workspace: no change; the card is a Web UI concern and the timing still
  comes from the host-projected deadline in the tool event payload.
• Peer Device Mode: the timing slot still respects
  canSubmitUserQuestionsOnSurface; a peer without userQuestionInteraction
  renders no countdown (and no settled label) instead of offering a control it
  cannot use.
• Remote control / Detached Dispatch: unchanged; both render their own surfaces,
  not this card. Not exercised end to end in this PR.

Risks

• waitTiming is a new optional AskUser prop; headerTrailing is unchanged for
  other consumers. The removed control.askUser.descriptionMaxWidth entry was only
  a component token claim — the token itself is still pinned by the design-tokens
  contract test.
• The countdown still disappears once an interaction is acknowledged, by design:
  the host cancels the timeout at that point. With the question timeout disabled the
  card now says No time limit instead of rendering nothing.
• Mobile surfaces render their own question card and are unaffected.

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