Xmlgui is only needed for the tools.

--- CMakeLists.txt.orig	2025-06-21 11:46:33 UTC
+++ CMakeLists.txt
@@ -172,8 +172,12 @@ else()
         IconThemes
         ${PLASMA_COMPONENT}
         TextWidgets
-        XmlGui
     )
+    if(BUILD_TOOLS)
+        list(APPEND KF_PRIVATE_COMPONENTS
+            XmlGui
+        )
+    endif()
     find_package(KF${QT_MAJOR_VERSION} ${KF_MIN_VERSION} REQUIRED COMPONENTS ${KF_PRIVATE_COMPONENTS} ${KF_PUBLIC_COMPONENTS})
 
     macro(ecm_add_executable)