Add Dockerfile, TrueNAS SCALE compose file and image publishing on release

Dockerfile

@@ -0,0 +1,20 @@
+# syntax=docker/dockerfile:1
+# Packages the binary deploy/build.sh already built (dist/bin/linux_<arch>/beach), so no
+# emulation is needed. Build it with:  sh deploy/build.sh && docker buildx build .
+#
+# Beach runs as root in the container: to start and stop containers it must read the
+# Docker socket, and the socket's group id differs from host to host. smartmontools is
+# there for the optional "smartctl" source (it also needs the devices passed in).
+FROM alpine:3.22
+ARG TARGETARCH
+LABEL org.opencontainers.image.title="Beach" \
+      org.opencontainers.image.description="One-page control panel for a homelab: containers, pools, disks and tunnels" \
+      org.opencontainers.image.source="https://git.veillax.com/Veillax/beach" \
+      org.opencontainers.image.licenses="MIT"
+RUN apk add --no-cache ca-certificates smartmontools \
+ && mkdir /data
+COPY dist/bin/linux_${TARGETARCH}/beach /beach
+VOLUME ["/data"]
+EXPOSE 8095
+ENTRYPOINT ["/beach"]
+CMD ["-listen", ":8095", "-data", "/data/beach.db"]