Fix armv7 docker helper build

docker/Dockerfile

@@ -22,12 +22,22 @@ FROM node:22-bookworm-slim
 WORKDIR /app
 
 ARG TARGETARCH
+ARG TARGETVARIANT
 ARG KUBECTL_VERSION=v1.31.8
 ARG HELM_VERSION=v3.18.6
 
 RUN apt-get update \
   && apt-get install -y --no-install-recommends ca-certificates curl tar gzip \
-  && case "$TARGETARCH" in amd64|arm64) export ARCH="$TARGETARCH" ;; *) echo "Unsupported TARGETARCH: $TARGETARCH" >&2; exit 1 ;; esac \
+  && case "$TARGETARCH" in \
+    amd64|arm64) export ARCH="$TARGETARCH" ;; \
+    arm) \
+      if [ "${TARGETVARIANT:-}" = "v7" ]; then \
+        export ARCH="arm"; \
+      else \
+        echo "Unsupported TARGETARCH/TARGETVARIANT: $TARGETARCH/${TARGETVARIANT:-}" >&2; exit 1; \
+      fi ;; \
+    *) echo "Unsupported TARGETARCH/TARGETVARIANT: $TARGETARCH/${TARGETVARIANT:-}" >&2; exit 1 ;; \
+  esac \
   && curl -fsSL -o /usr/local/bin/kubectl "https://dl.k8s.io/release/${KUBECTL_VERSION}/bin/linux/${ARCH}/kubectl" \
   && chmod +x /usr/local/bin/kubectl \
   && curl -fsSL "https://get.helm.sh/helm-${HELM_VERSION}-linux-${ARCH}.tar.gz" -o /tmp/helm.tgz \