Netmaker add-on: pull prebuilt image from Gitea registry

Home Assistant add-on that joins the instance to a Netmaker network via
netclient. Distributed as a repository add-on using a prebuilt arm64 image
(gitea.savant.io/homeassistant/netmaker) to avoid local buildx.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

netmaker/Dockerfile

@@ -0,0 +1,63 @@
+ARG BUILD_FROM=ghcr.io/hassio-addons/base/amd64:10.1.1
+# hadolint ignore=DL3006
+FROM ${BUILD_FROM}
+
+# Set shell
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
+
+# Setup base
+ARG BUILD_ARCH=amd64
+ARG NETCLIENT_VERSION="v1.6.0"
+# hadolint ignore=DL3018
+RUN \
+    apk add --no-cache \
+        iproute2 \
+        iptables \
+        ip6tables \
+        nftables \
+        wireguard-tools \
+        openresolv \
+        coreutils \
+    \
+    && ln -sf /sbin/xtables-nft-multi /sbin/ip6tables \
+    && ln -sf /sbin/xtables-nft-multi /sbin/iptables \
+    \
+    && if [ "${BUILD_ARCH}" = "aarch64" ]; then ARCH="arm64"; fi \
+    && if [ "${BUILD_ARCH}" = "amd64" ]; then ARCH="amd64"; fi \
+    \
+    && curl -L -s -o /opt/netclient \
+        "https://github.com/gravitl/netclient/releases/download/${NETCLIENT_VERSION}/netclient-linux-${ARCH}" \
+    && chmod 0755 /opt/netclient \
+    && ln -sf /opt/netclient /usr/bin/netclient
+
+# Copy root filesystem
+COPY rootfs /
+
+HEALTHCHECK \
+    CMD healthcheck
+
+# Build arguments
+ARG BUILD_ARCH
+ARG BUILD_DATE
+ARG BUILD_DESCRIPTION
+ARG BUILD_NAME
+ARG BUILD_REF
+ARG BUILD_REPOSITORY
+ARG BUILD_VERSION
+
+# Labels
+LABEL \
+    io.hass.name="${BUILD_NAME}" \
+    io.hass.description="${BUILD_DESCRIPTION}" \
+    io.hass.arch="${BUILD_ARCH}" \
+    io.hass.type="addon" \
+    io.hass.version=${BUILD_VERSION} \
+    org.opencontainers.image.title="${BUILD_NAME}" \
+    org.opencontainers.image.description="${BUILD_DESCRIPTION}" \
+    org.opencontainers.image.vendor="Home Assistant Community Apps" \
+    org.opencontainers.image.licenses="MIT" \
+    org.opencontainers.image.source="https://github.com/${BUILD_REPOSITORY}" \
+    org.opencontainers.image.documentation="https://github.com/${BUILD_REPOSITORY}/blob/main/README.md" \
+    org.opencontainers.image.created=${BUILD_DATE} \
+    org.opencontainers.image.revision=${BUILD_REF} \
+    org.opencontainers.image.version=${BUILD_VERSION}