fix(ui): fill collapsed progress-card hover to the composer edge (#129869)

Collapsed, the composer progress card's hover highlight painted only the
<summary> band, leaving slivers of the resting background in the underlap
strip and the arcs beside the composer's rounded corners. Move the
collapsed hover fill to the card container (clipped to the full rounded
shape, extending under the composer) and keep the summary-scoped fill for
the expanded state.

ui/src/styles/chat/composer-progress.css

@@ -225,7 +225,12 @@
 }
 
 @media (hover: hover) and (pointer: fine) {
-  .session-progress-card__summary:hover {
+  /* Collapsed, the visible card extends past the summary (underlap arcs beside
+     the composer's rounded corners), so the highlight lives on the container to
+     fill the whole shape; a summary-only fill leaves slivers of the resting
+     background at those corners. */
+  .session-progress-card--composer:not([open]):hover,
+  .session-progress-card--composer[open] .session-progress-card__summary:hover {
     background: color-mix(
       in srgb,
       var(--text-strong) 5%,