Refine iOS layout editor preview behavior

- Clip the portrait editor controller deck to its bounds so draggable
  buttons cannot be dragged visually into the top game viewport area.
  The stored positions remain normalized to the deck and clamped to 0...1.

- No other changes: skin environment injection, orientation request helper,
  portrait/landscape editor layouts, and all toolbar/undo/save/reset behavior
  remain as implemented in the previous commit.

Author: J1coding

app/src/main/swift/Views/Settings/PadLayoutEditView.swift

@@ -130,6 +130,7 @@ struct PadLayoutEditView: View {
                         editorPortraitContent(areaW: geo.size.width, areaH: padHeight)
                     }
                     .frame(height: padHeight)
+                    .clipped()
                 }
 
                 VStack {