fix: gate kwin's X11-only helpers and the QUiLoader scripted-effects KCM

kwin compiles further; the remaining failure has moved into the native
qtwaylandscanner_kde sub-build (host/target flag leakage), not the target
sources.

killer and dialoghelper both include <private/qtx11extras_p.h> unguarded
and call QX11Info / XCB_CURRENT_TIME behind a RUNTIME platformName()==xcb
check that is always false on a Wayland-only session. Note src/main.cpp
does this CORRECTLY -- #if KWIN_BUILD_X11 around both the include and
every use -- so the guard is upstream's own convention and these two
helpers simply were not updated. Core kwin needed no change.

The missing private header also explains a misleading second symptom: on
failing to find it the compiler fell back to the HOST /usr/include/qt6 and
reported 'Qt has not been ported to this OS', which looks like an
unrelated toolchain fault but is the same missing header.

kcm_kwin4_genericscripted includes QUiLoader from qttools, which is not
ported. Dropping only the Qt::UiTools link left the include behind, so the
whole target is gated. It is the settings dialog for scripted effects; the
effects themselves are unaffected. Remove once qttools lands.

local/recipes/kde/kwin/recipe.toml

@@ -90,6 +90,43 @@ sed -i '/include(ECMQmlModule)/s/^/#/' "${COOKBOOK_SOURCE}/CMakeLists.txt" 2>/de
 sed -i '/^    UiTools$/d' "${COOKBOOK_SOURCE}/CMakeLists.txt"
 sed -i '/^    Qt::UiTools$/d' "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
 
+# dialoghelper is X11-specific but is built unconditionally, even with
+# KWIN_BUILD_X11=OFF. It includes <private/qtx11extras_p.h> and <xcb/xcb.h> at
+# top level and calls QX11Info::setAppUserTime / XCB_CURRENT_TIME, all behind a
+# RUNTIME check (platformName() == "xcb") that is always false on a Wayland-only
+# session. qtbase does not install the private X11 interop header for this
+# target, so the build fails:
+#   dialoghelper.cpp:22:10: fatal error: private/qtx11extras_p.h: No such file
+# and the compiler then falls back to the HOST /usr/include/qt6, which errors
+# with "Qt has not been ported to this OS" -- a misleading second symptom of the
+# same missing header, not an independent problem.
+# Upstream oversight: the helper should be gated on KWIN_BUILD_X11.
+# Idempotent: once commented, ^add_subdirectory no longer matches.
+sed -i 's/^add_subdirectory(dialoghelper)/#add_subdirectory(dialoghelper)/' \
+    "${COOKBOOK_SOURCE}/src/helpers/CMakeLists.txt" 2>/dev/null || true
+
+# killer: same story as dialoghelper -- includes <private/qtx11extras_p.h>
+# unguarded. Note src/main.cpp does this CORRECTLY (#if KWIN_BUILD_X11 around
+# the include and every use), so the guard is upstream's own convention; the two
+# helpers simply were not updated. Core kwin needs no change.
+sed -i 's/^add_subdirectory(killer)/#add_subdirectory(killer)/' \
+    "${COOKBOOK_SOURCE}/src/helpers/CMakeLists.txt" 2>/dev/null || true
+
+# kcm_kwin4_genericscripted (config UI for scripted effects) includes QUiLoader
+# from qttools, which is not ported. Dropping only the Qt::UiTools link left the
+# include, so drop the target too. This is a settings dialog for scripted
+# effects; the effects themselves are unaffected. Remove once qttools lands.
+sed -i 's/^set(kcm_kwin4_genericscripted_SRCS/#set(kcm_kwin4_genericscripted_SRCS/' \
+    "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
+sed -i 's/^qt_add_dbus_interface(kcm_kwin4_genericscripted_SRCS/#qt_add_dbus_interface(kcm_kwin4_genericscripted_SRCS/' \
+    "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
+sed -i 's/^add_library(kcm_kwin4_genericscripted/#add_library(kcm_kwin4_genericscripted/' \
+    "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
+sed -i '/^target_link_libraries(kcm_kwin4_genericscripted$/,/^)/ s/^/#/' \
+    "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
+sed -i 's/^install(TARGETS kcm_kwin4_genericscripted/#install(TARGETS kcm_kwin4_genericscripted/' \
+    "${COOKBOOK_SOURCE}/src/kcms/common/CMakeLists.txt" 2>/dev/null || true
+
 # TEMPORARY DEBT -- systembell (audible bell) is the ONLY consumer of Canberra
 # in KWin (src/plugins/systembell/*). kwin's find_package(Canberra REQUIRED) is
 # ungated, so the whole compositor fails to configure over one optional plugin.