ci: isolate caches and trust ARM Alpine keys [CI] [SKIP TESTS]

Signed-off-by: JustMe <mr.toing@outlook.com>

ci/build-dev-image.sh

@@ -59,7 +59,9 @@ context="$work/$component"
 local_image="localhost/moshiro-$component:dev-$arch-check"
 node_rid="linux-musl-x64"
 [[ "$arch" == arm64 ]] && node_rid="linux-musl-arm64"
-nuget_cache="${NUGET_PACKAGES:-/home/justme/.nuget/packages}"
+# Keep writable NuGet caches isolated per parallel build (component + arch).
+# Reuse still applies across pipeline runs without concurrent restore races.
+nuget_cache="$base_home/nuget-packages"
 mkdir -p "$nuget_cache"
 
 # A stable timestamp lets a retry of the same commit reuse the publish layer.