@

fix(D.2b): arrow swap, centered menu text, scrollbar-to-top, Send caption

- scroll arrows: native sprites are opposite (0x06004C6C up / 0x06004C69 down) per live
  visual — swap the assignment, drop the V-flip.
- menu labels centered vertically in each 17px row (was top-aligned, looked corrupt).
- scrollbar pulled up to the panel top so the top arrow meets the window border and the
  max/min button lines up with it (the 6px dat offset left a gap after the resize-bar reclaim).
- Send button: the dat sprite 0x06001915 is a blank gold frame (export-confirmed), so add a
  generic optional Label/LabelFont to UiDatElement and draw "Send" centered on it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
@

src/AcDream.App/UI/UiChannelMenu.cs

@@ -134,11 +134,12 @@ public sealed class UiChannelMenu : UiElement
                 bool selected = Items[i].Channel is { } c && c == Selected;
                 DrawSprite(ctx, resolve, selected ? ItemHighlightSprite : ItemNormalSprite, x, y, ColW, ItemH);
             }
+            float textY = (ItemH - LineH()) * 0.5f;   // center the label in its row
             for (int i = 0; i < Items.Length; i++)
             {
                 int col = i / Rows, row = i % Rows;
                 bool avail = Items[i].Channel is { } c && IsAvailable(c);
-                DrawLabel(ctx, Items[i].Label, 4f + col * ColW, top + row * ItemH,
+                DrawLabel(ctx, Items[i].Label, 4f + col * ColW, top + row * ItemH + textY,
                           avail ? TextColorAvailable : TextColorGhosted);
             }
         }