Game/Telegram review polish: USSR flag, touch drag ghost, TG fullscreen header

Backlog item 2 of ~4 (owner review pass):
- USSR flag emblem redrawn (canonical hammer & sickle, scaled down 1.5x
  below the star).
- Touch drag-and-drop: enlarge the drag ghost 1.5x on touch only (the finger
  hides the tile); suppress the iOS tap-highlight that lingered on a rack tile
  sliding into a dragged tile's slot.
- Telegram fullscreen: its native nav no longer hides our header -- the header
  drops below the content-safe-area top inset and the menu (hamburger) lifts
  into the nav band, centred (--tg-content-top from the SDK inset + a
  tg-fullscreen class; new telegram.ts helper + app wiring).

Tests: UI check/test:unit/build + full e2e (60) green. The iOS tap-highlight
fix and the TG-fullscreen layout want on-device verification on the deploy.

ui/public/flag-ussr.svg

@@ -1,14 +1,16 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 16" role="img" aria-label="СССР">
   <rect width="24" height="16" fill="#cc0000"/>
-  <!-- five-pointed star (filled, slightly smaller) -->
-  <path fill="#ffd700" d="M6 2.4l.78 1.6 1.76.26-1.27 1.24.3 1.75L6 6.63l-1.57.82.3-1.75L3.46 4.5l1.76-.26z"/>
-  <!-- schematic hammer & sickle (a sketch, thin strokes) -->
-  <g fill="none" stroke="#ffd700" stroke-width="0.5" stroke-linecap="round" stroke-linejoin="round">
-    <!-- sickle: an elongated semicircle blade with a short handle -->
-    <path d="M8.2 7.4a3 3 0 1 1-3.3 3.9"/>
-    <path d="M4.9 11.3l-.8.7"/>
-    <!-- hammer: a T-shape (handle + head) crossing the sickle -->
-    <path d="M5.1 11 8.1 8"/>
-    <path d="M7.2 7.1 9 8.9"/>
+  <!-- small five-pointed star -->
+  <path fill="#ffd700" d="M6 1.9 L6.32 2.86 7.33 2.87 6.51 3.47 6.82 4.43 6 3.84 5.18 4.43 5.49 3.47 4.67 2.87 5.68 2.86 Z"/>
+  <g fill="none" stroke="#ffd700" stroke-linecap="round" stroke-linejoin="round" transform="translate(6.8 6) scale(0.667) translate(-6.8 -6)">
+    <!-- sickle: a crescent blade + short handle, mirrored across a diagonal through its centre
+         so it reads as the canonical sickle (blade sweeping down-right); the hammer is untouched -->
+    <g transform="matrix(0 1 1 0 -2.8 2.8)">
+      <path stroke-width="0.6" d="M8.1 6.0 C 10.7 6.9 10.9 11.3 7.2 13.3 C 5.1 14.5 2.9 13.2 2.7 10.9"/>
+      <path stroke-width="0.6" d="M8.1 6.0 l 0.85 -0.95"/>
+    </g>
+    <!-- hammer: handle (down-right) + head (a short bar) at ~90°, crossing the sickle -->
+    <path stroke-width="0.78" d="M4.6 8.4 L 8.4 12.9"/>
+    <path stroke-width="0.78" d="M3.25 9.05 L 5.95 7.05"/>
   </g>
 </svg>