build-redbear: skip llvm21 pre-cook for mini/grub (Mesa/graphics dep)

llvm21 is a Mesa (graphics) build dep used by mesa and libepoxy for
shader compilation. It is NOT required for the redbear-mini or
redbear-grub text-only targets, but the pre-cook list was cooking
it unconditionally, adding a 30+ minute stall to every mini build.

Pre-cook only relibc + icu for mini/grub. The full desktop chain
(including llvm21) is still pre-cooked for redbear-full.

local/scripts/build-redbear.sh

@@ -233,11 +233,12 @@ bash "$PROJECT_ROOT/local/scripts/build-preflight.sh" --config="$CONFIG" ${REDBE
 # --with-package-deps resolves ALL transitive deps; pre-cooking ensures
 # the repo has valid pkgars before make live processes the full graph.
 # Only pre-cook the desktop chain for redbear-full; mini/grub don't need it.
+# llvm21 is a Mesa (graphics) dep — only needed when the Mesa chain is in scope.
 echo ">>> Pre-cooking critical packages..."
 if [ "$CONFIG" = "redbear-full" ]; then
     PRECOOK_PKGS="relibc icu llvm21 mesa libdrm libepoxy redox-drm lcms2 libdisplay-info libxcvt kwin sddm qtbase"
 else
-    PRECOOK_PKGS="relibc icu llvm21"
+    PRECOOK_PKGS="relibc icu"
 fi
 for pkg in $PRECOOK_PKGS; do
     if [ ! -f "$PROJECT_ROOT/repo/x86_64-unknown-redox/$pkg.pkgar" ]; then