M9.R.15q.5.8: kwin drops KCMS-gated buildDeps when KWIN_BUILD_KCMS=OFF

Upstream kwin 6.2.5's CMakeLists.txt:104 gates
``find_package(KF6 ... Declarative KCMUtils NewStuff Service XmlGui)``
behind the KWIN_BUILD_KCMS option. Since the recipe sets
KWIN_BUILD_KCMS=OFF (M9.R.15q.4.7) those frameworks are not
required at find_package time, so we don't need to drag them
through the from-source auto-recurse either.

Drop kdeclarative + kcmutils + knewstuff from kwin's buildDeps.
Keep kpackage + kirigami because the QML side of kwin's effects
still uses them outside the KCMS gate.

Closes the attica Qt-version-skew trip (the nix attica derivation
is built against Qt 6.10; ours is on 6.8.1) since knewstuff is no
longer dragged in.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: zah

recipes/packages/source/kwin/repro.nim

@@ -304,9 +304,13 @@ package kwinSource:
     "kauth >=6.0"
     "kcolorscheme >=6.0"
     "kidletime >=6.0"
-    "kdeclarative >=6.0"
-    "kcmutils >=6.0"
-    "knewstuff >=6.0"
+    ## M9.R.15q.5.8 — kdeclarative + kcmutils + knewstuff are
+    ## conditionally required ONLY when KWIN_BUILD_KCMS=ON (see kwin
+    ## upstream CMakeLists.txt:104). With KWIN_BUILD_KCMS=OFF (which
+    ## the cacheVars below set) these are NOT looked up and so the
+    ## from-source auto-recurse should not need to build them. We keep
+    ## kpackage + kirigami because the QML side of kwin's effects
+    ## still uses them.
     "kpackage >=6.0"
     "kirigami >=6.0"
     ## hwdata (RUNTIME) for monitor vendor-ID mapping.