Fix Qt-only build without KF5

The BUILD_WITH_KF5 option was checked with DEFINED, so passing -DBUILD_WITH_KF5=OFF still entered the KF5 setup path.

Skip the KF5 setup when disabled and provide small Qt-only replacements for the KDE color widgets used by .ui files in that build mode.

Assisted-by: pi coding agent / Mika (OpenAI GPT-5.5)

cmake/fetch_kdeaddons.cmake

@@ -16,7 +16,7 @@
 
 message(" - fetch_kdeaddons")
 
-if(DEFINED BUILD_WITH_KF5)
+if(BUILD_WITH_KF5)
   Include(FetchContent)
 
   option(BUILD_KF5 "Build KF5 libraries, use system ones otherwise" YES)

cmake/qet_compilation_vars.cmake

@@ -724,6 +724,15 @@ set(QET_SRC_FILES
   ${QET_DIR}/sources/xml/terminalstriplayoutpatternxml.h
   )
 
+if(NOT BUILD_WITH_KF5)
+  list(APPEND QET_SRC_FILES
+    ${QET_DIR}/sources/ui/nokde/kcolorbutton.cpp
+    ${QET_DIR}/sources/ui/nokde/kcolorbutton.h
+    ${QET_DIR}/sources/ui/nokde/kcolorcombo.cpp
+    ${QET_DIR}/sources/ui/nokde/kcolorcombo.h
+  )
+endif()
+
 set(TS_FILES
   ${QET_DIR}/lang/qet_ar.ts
   ${QET_DIR}/lang/qet_ca.ts