Stage 17 (contour round 4a): quick fixes

- #4 bag label: '{n} in the bag' / 'Bag is empty' (was 'Bag {n}')
- #6 allow a single trailing dot in display names (backend + UI regex + tests)
- #1 double-tap zooms toward the tapped cell, not the top-left
- #8 shuffle fires a short multi-pulse haptic
- #11 highlighted/flashing tiles darken their bottom edge too (shadow joins the flash)
- #13 toast slides up from the bottom and fades out
- #7 hide the logout button (kept wired behind `hidden`)
- #16 admin game seats: left-align numeric columns, clarify the 'Hints used' header

ui/src/game/Board.svelte

@@ -33,7 +33,7 @@
     locale: Locale;
     focus: { row: number; col: number } | null;
     oncell: (row: number, col: number) => void;
-    ontogglezoom: () => void;
+    ontogglezoom: (row: number, col: number) => void;
   } = $props();
 
   const Z = 1.85;
@@ -65,7 +65,7 @@
   function onTap(row: number, col: number) {
     const now = Date.now();
     if (now - lastTap < 300) {
-      ontogglezoom();
+      ontogglezoom(row, col); // zoom toward the double-tapped cell, not the top-left
       lastTap = 0;
       return;
     }
@@ -172,6 +172,9 @@
   }
   .cell.hl {
     background: var(--tile-recent);
+    /* The bottom edge goes darker than the highlighted fill (not lighter, as the plain
+       --tile-edge would), so the tile still reads as raised. */
+    box-shadow: inset 0 -2px 0 rgba(0, 0, 0, 0.32);
   }
   .cell.flash {
     /* Two flashes to draw the eye, then settle back to normal so it does not distract. */
@@ -181,9 +184,11 @@
     0%,
     100% {
       background: var(--tile-bg);
+      box-shadow: inset 0 -2px 0 var(--tile-edge);
     }
     50% {
       background: var(--tile-recent);
+      box-shadow: inset 0 -2px 0 rgba(0, 0, 0, 0.32);
     }
   }
   /* cqw fonts are sized against the fixed viewport, so labels stay a constant size as