Fix kiosk weekend visibility and landscape weekday layout

The kiosk deliberately ignored calendar.showWeekend when it was built,
treating the parent's toggle as print-only -- but that's not what parents
actually expect: hiding the weekend on the dashboard should hide it on
the tablet too. kiosk.js now toggles weekendWrap's hidden class the same
way the parent editor does.

Separately, weekdayBoard's auto-fit/minmax(240px) grid only fit 4 columns
on real tablet landscape widths (~1024-1180px), pushing Friday to a
second row. Since weekdayBoard always holds exactly 5 day-cards, forcing
repeat(5, 1fr) once there's clearly tablet-landscape width (960px+,
excludes large phones in landscape) fits all 5 comfortably instead of
relying on auto-fit's width heuristic.

Verified both at real tablet landscape sizes (1024x768, 1180x820) with
the Browser tool: 5 weekday columns fit in one row, and the weekend
section correctly appears/disappears with showWeekend.

public/kiosk.html

@@ -19,6 +19,18 @@
   .board{ grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
   .task-text{ font-size: 1.02rem; }
 
+  /* weekdayBoard always holds exactly 5 day-cards (Mon-Fri) — on a tablet
+     in landscape there's room for all 5 side by side, but the 240px
+     auto-fit minimum (sized for narrower/portrait views) was only letting
+     4 fit, pushing Friday to a second row. Force exactly 5 columns once
+     there's clearly tablet-landscape width to do it justice; narrower
+     views keep the auto-fit wrapping behavior above. 960px excludes large
+     phones in landscape (~926px max) while covering real tablets.
+  */
+  @media (orientation: landscape) and (min-width: 960px) {
+    .board{ grid-template-columns: repeat(5, 1fr); }
+  }
+
   /* Full-bleed standalone launch: respect notches/home-indicator, and stop
      iOS's rubber-band overscroll from flashing white space at the edges. */
   body{