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/src/components/Header.svelte

@@ -89,4 +89,20 @@
     transform: rotate(45deg);
     margin-left: 3px;
   }
+  /* Telegram fullscreen: its native nav overlays the top of the viewport (height
+     --tg-content-top, set from the content-safe-area inset). Drop the header content below the
+     nav and lift the menu up into the nav band, centred — Telegram's own controls sit in the
+     corners, leaving the centre clear (Stage 17). */
+  :global(html.tg-fullscreen) .bar {
+    padding-top: var(--tg-content-top);
+  }
+  :global(html.tg-fullscreen) .end {
+    position: fixed;
+    top: 0;
+    left: 50%;
+    transform: translateX(-50%);
+    height: var(--tg-content-top);
+    justify-content: center;
+    z-index: 30;
+  }
 </style>