uniweb: Restrict menu page types to uniweb pages

uniweb/models.py

@@ -52,7 +52,10 @@ class GallerySectionBlock(blocks.StructBlock):
 
 class MenuItemBlock(blocks.StructBlock):
     name = blocks.CharBlock(label="název")
-    page = blocks.PageChooserBlock(label="stránka")
+    page = blocks.PageChooserBlock(
+        label="stránka",
+        page_type=["uniweb.UniwebHomePage", "uniweb.UniwebFlexiblePage"],
+    )
 
     class Meta:
         label = "stránka"