feat(composer): one collapsible question card for both deliveries

[Tryanks]

Summary

A long agent question (Claude AskUserQuestion, Codex requestUserInput) used to render its whole text unbounded above the composer; on a phone it filled the screen and pushed the input off it. Both deliveries now share one card: a one-line strip that stays, and an answer area that folds away and scrolls inside a share of the window.

 Composer
   render_user_input_panel(pending, window)
-    blocking  → full card: header, question (unbounded), options (240px scroll), custom answer, prev/next/done, pager
-    async     → strip + chips, collapsible, dismissible
+    strip: icon · title · (collapsed: truncated question) · prev · n/total · next · ▾/▴ · (async: ✕)
+    body (when expanded):
+      scroll area, max_h = clamp(40% of viewport, 120..360)
+        question text
+        option rows (digit hints only while blocking)
+      custom answer
+      hint · Done (multi-select, all answered)

on(new request)   ui_expanded = delivery.is_blocking()
on(strip click)   ui_expanded = !ui_expanded
on(prev/next)     ui_expanded = true; move
on(✕, async only) hide locally; "Question from the agent" button brings it back

Behaviour that stays: single-select auto-advances and submits, multi-select finishes with Done, digits 1-9 in the empty composer answer a blocking question, Enter in the composer submits the custom answer while blocked.

Evidence

• Before: the screenshot in the request — a blocking question's text filling a phone screen, composer off-screen.
  After: desktop app at 700×620 with a ~1200-char AskUserQuestion from Claude Code: card capped at 248 px, question scrolls inside it, composer visible; strip click collapses it to one line showing Design We are considering the overall design direc…, click again restores it.

• Tests (cargo nextest run -p tcode-ui user_input): 4 passed.

  • async_question_strip_controls kept: strip buttons act once without reaching the strip underneath; async arrives closed, can be hidden, has a way back. Selectors renamed ui-async-* → ui-* since they are no longer async-only.
  • blocking_question_collapses_but_stays added: blocking arrives open, folds, never shows ✕, prev/next reopen it.

Checks run: cargo fmt --all --check, cargo clippy -p tcode-ui --all-targets --locked -- -D warnings, cargo nextest run -p tcode-ui. Not run: full-workspace clippy (only crates/ui changed), dark theme, a real phone or the phone example (it needs a paired host; the compact path differs only in touch sizes).

Merge Danger

Door: two-way

One component, no protocol or state change outside the composer; revert is a single commit.

Blast Radius: composer

Visual change to every agent question on every client. Async questions lose the chip layout and gain option descriptions and the same rows as blocking ones.