fix(suggest): let the dropdown out of the hero panel

.heroPanel had overflow: hidden to clip its artwork and scrim to the
rounded corners. It clipped the suggestion dropdown too. Measured on
staging with the flag on: the list runs 482 to 802, the panel ends at
624 — so 178px of 320 was cut off, about half the options, with nothing
on screen to say anything was missing.

The two things that actually needed clipping now round themselves:
.heroArt gets border-radius: inherit plus its own overflow, and the
::before scrim inherits the radius. Below 860px the artwork is a band
flush with the top of the panel rather than a layer covering it, so it
takes the top two corners only — inheriting all four would leave it
floating with rounded corners against the copy.

Nothing else depended on the panel clipping: .valueProps below it is
entirely static, so a positioned dropdown paints above it without a
z-index fight.

The regression test asserts the LAST option is the element actually
painted at its own coordinates. toBeVisible() would not have caught
this — it checks for a non-empty box and visibility, and an ancestor's
overflow clips neither. elementFromPoint catches clipping and occlusion
alike.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj

nextjs-app/components/HomeView.module.css

@@ -90,7 +90,18 @@
   isolation: isolate;
   background: var(--hero-ground);
   border-radius: var(--radius-xl);
-  overflow: hidden;
+  /*
+   * Deliberately NOT overflow: hidden.
+   *
+   * It used to be, to clip the artwork and the scrim to the rounded corners —
+   * and it also clipped the search box's suggestion dropdown, which is 320px
+   * tall against 145px of panel below the input. Roughly half the list was cut
+   * off with no indication anything was missing.
+   *
+   * The two things that actually needed clipping round themselves instead, so
+   * the panel can let a dropdown out. Anything absolutely positioned inside
+   * this panel and taller than the space below it depends on this.
+   */
 }
 
 .heroContent {
@@ -107,6 +118,10 @@
   position: absolute;
   inset: 0;
   z-index: 0;
+  /* Rounds itself, because the panel no longer clips it. inset: 0 makes this
+     exactly the panel's own corners. */
+  border-radius: inherit;
+  overflow: hidden;
 }
 
 .heroArt picture,
@@ -143,6 +158,9 @@
   inset: 0;
   z-index: 1;
   pointer-events: none;
+  /* Same reason as .heroArt: the panel stopped clipping, so the scrim keeps
+     its own corners rather than squaring off over the panel's. */
+  border-radius: inherit;
   background: linear-gradient(
     to right,
     var(--hero-ground) 0%,
@@ -331,6 +349,10 @@
     position: static;
     order: -1;
     height: 13rem;
+    /* Top corners only. Here the artwork is a band flush with the top of the
+       panel, not a layer covering it — inheriting all four would leave it
+       floating with rounded bottom corners against the copy below. */
+    border-radius: var(--radius-xl) var(--radius-xl) 0 0;
   }
   /* The band crop puts the schoolhouse at 73% across — reported by
      scripts/build-hero-images.js, which derives it from the crop box rather