feat(ui): support scaling of labels and images

Modify width() and height() methods to multiply by m_scale for both Label and Image. Rename internal dimensions to m_real_width and m_real_height for clarity. Adjust Button foreground position to vertically center when label is scaled.

include/Cubed/ui/label.hpp

@@ -36,8 +36,8 @@ protected:
 private:
     TextStyle m_text;
     UIVertexData m_data;
-    float m_width = 0.0f;
-    float m_height = 0.0f;
+    float m_real_width = 0.0f;
+    float m_real_height = 0.0f;
     float m_offset_x = 0.0f;
     float m_offset_y = 0.0f;
     void update_vertices();