Convert to s6-overlay v2 (cont-init.d + services.d) for base 10.1.1

Base image ghcr.io/hassio-addons/base 10.1.1 uses s6-overlay v2, which ignores
the s6-rc.d (v3) structure — netclient never started. Reimplement as v2:
cont-init.d/10-persist + 20-join run before services.d/netclient (daemon).
Release 0.1.1.

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

netmaker/rootfs/usr/bin/healthcheck

@@ -1,4 +1,4 @@
-#!/command/with-contenv bashio
+#!/usr/bin/with-contenv bashio
 # shellcheck shell=bash
 export LOG_FD