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/components/Toast.svelte

@@ -1,9 +1,20 @@
 <script lang="ts">
+  import { fade, fly } from 'svelte/transition';
   import { app } from '../lib/app.svelte';
+
+  const dur = $derived(app.reduceMotion ? 0 : 260);
 </script>
 
 {#if app.toast}
-  <div class="toast {app.toast.kind}" role="status" aria-live="polite">{app.toast.text}</div>
+  <div
+    class="toast {app.toast.kind}"
+    role="status"
+    aria-live="polite"
+    in:fly={{ y: 32, duration: dur }}
+    out:fade={{ duration: dur }}
+  >
+    {app.toast.text}
+  </div>
 {/if}
 
 <style>