fix(messaging-ui): composer no longer stretches the send/attach buttons

The textarea swap made the composer row tall and dragged the controls with it.
Three causes, all fixed:

- No box-sizing anywhere in the stylesheet, so `min-height: 38px` on a padded,
  bordered textarea rendered ~58px (content-box adds 18px padding + 2px border
  on top). The textarea is now border-box with a 40px min-height — the same
  height the old single-line input had.
- .miu-composer-row is display:flex with no align-items, so it defaulted to
  `stretch` and the buttons — neither of which declared a height — grew to the
  row. Now align-items: flex-end, so controls stay pinned to the bottom while
  the box grows upward (WhatsApp behaviour), with an explicit 40px on both.
  The send height is scoped to .miu-composer so modal/settings buttons keep
  their own sizing.
- The auto-grow effect set height = scrollHeight, which under content-box
  double-counted padding on every keystroke. It now compensates for the border
  explicitly, correct under border-box.

Bumped to 0.1.11. SDK suite: 17 files / 98 tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/iios-messaging-ui/src/components/composer.tsx

@@ -54,11 +54,14 @@ export function Composer({
   const inputRef = useRef<HTMLTextAreaElement>(null);
 
   // Grow with the content up to the CSS max-height, then scroll — a chat box, not a fixed field.
+  // The box is border-box, but scrollHeight excludes the border, so add it back or every measure
+  // lands a couple of pixels short and the textarea shows a scrollbar it doesn't need.
   useEffect(() => {
     const el = inputRef.current;
     if (!el) return;
     el.style.height = 'auto';
-    el.style.height = `${el.scrollHeight}px`;
+    const border = el.offsetHeight - el.clientHeight;
+    el.style.height = `${el.scrollHeight + border}px`;
   }, [draft]);
 
   /**