fix: the 3D scene is drawn in the wrong view for the first half second of startup (#15830)

src/slic3r/GUI/GUI_App.cpp

@@ -865,6 +865,9 @@ void GUI_App::post_init()
         plater_->canvas3D()->enable_render(false);
         mainframe->select_tab(TAB_ID_PREPARE);
         plater_->select_view_3D("3D");
+        // The first render happens before the queued new_project() sets the same view.
+        plater_->get_camera().select_view("topfront");
+        plater_->get_camera().requires_zoom_to_bed = true;
         //BBS init the opengl resource here
         if (!plater_->canvas3D()->get_wxglcanvas()->IsShownOnScreen() ||
             !plater_->canvas3D()->make_current_for_postinit()) {