icons/rest-api: load user theme

Change-Id: I23e302a56a13f19f8540e08ff30137db7cf4f676
JIRA-Ref: CMK-28547

Author: ottermata

cmk/gui/openapi/api_endpoints/icon/list_icons.py

@@ -23,7 +23,8 @@
     DomainObjectModel,
 )
 from cmk.gui.openapi.restful_objects.constructors import collection_href
-from cmk.gui.theme.current_theme import theme
+from cmk.gui.theme import make_theme
+from cmk.gui.userdb import load_custom_attr
 from cmk.gui.watolib.icons import all_available_icon_data
 
 
@@ -52,6 +53,10 @@ class IconCollectionModel(DomainObjectCollectionModel):
 
 def list_icons_v1(api_context: ApiContext) -> IconCollectionModel:
     """Show all icons."""
+    theme = make_theme(validate_choices=False)
+    theme.from_config(api_context.config.ui_theme)
+    if user_id := api_context.user_id:
+        theme.set(load_custom_attr(user_id=user_id, key="ui_theme", parser=str))
     return IconCollectionModel(
         domainType="icon",
         id="all",