fix(ui): the header search has room on a tablet

On touch the 44 px key cap and Go filled a 44 px pill edge to edge and the
placeholder was cut. The key cap is left out on touch (⌘K still works), the
pill grows to 52 px so a ring shows round Go, the box's floor counts the
controls beside the text, and Go drops to its icon by the column's width,
not the screen's.

frontend/src/components/PaletteLauncher.tsx

@@ -28,7 +28,8 @@ function useCap(): string {
 // words matched nothing.
 
 /** The key cap at the end of a search field. A button, so the pointer and a screen reader reach it
- *  too; left out of a phone's narrow header, where there is no keyboard to press it on. */
+ *  too; left out of a phone's narrow header and of every touch screen, where there is (usually) no
+ *  keyboard to press it on — on a tablet it was a 44 px box crowding the field. ⌘K still works. */
 export function PaletteKeycap() {
   const { t } = useTranslation();
   const cap = useCap();
@@ -37,7 +38,7 @@ export function PaletteKeycap() {
       onClick={openPalette}
       aria-label={`${t("palette.open")} (${cap})`}
       title={`${t("palette.open")} (${cap})`}
-      className="inline-flex h-6 shrink-0 items-center justify-center rounded-md border border-border px-1.5 font-mono text-3xs touch-target text-muted transition hover:border-accent/50 hover:text-fg @max-[640px]/appmain:hidden"
+      className="inline-flex h-6 shrink-0 items-center justify-center rounded-md border border-border px-1.5 font-mono text-3xs touch-target text-muted transition hover:border-accent/50 hover:text-fg pointer-coarse:hidden @max-[640px]/appmain:hidden"
     >
       {cap}
     </Pressable>