TG-fullscreen header: add height via padding (min-height wasn't binding), +12px breathing room

ui/src/components/Header.svelte

@@ -95,14 +95,16 @@
      it, BELOW the notch — lining them up vertically with Telegram's own back/menu controls,
      which sit in the band's corners (Stage 17). */
   :global(html.tg-fullscreen) .bar {
-    /* +6px over the content-safe band so Telegram's native controls aren't flush against
-       our header (owner's review tweak, Stage 17). */
-    min-height: calc(var(--tg-content-top) + 6px);
+    min-height: var(--tg-content-top);
     box-sizing: border-box;
     align-items: center;
     justify-content: center;
-    padding-top: var(--tg-safe-top);
-    padding-bottom: 0;
+    /* +12px of vertical breathing room (6 above / 6 below the centred content, on top of the
+       notch) so Telegram's native controls aren't flush against our header. Applied as
+       padding because the bar is sized by its content here, not by min-height (owner review
+       tweaks, Stage 17). */
+    padding-top: calc(var(--tg-safe-top) + 6px);
+    padding-bottom: 6px;
   }
   :global(html.tg-fullscreen) .spacer {
     display: none;