feat: ship verified platform upgrades with channel bundle releases

Package production dependencies per architecture for online and offline upgrades.
Validate dependencies and isolated backend startup before readiness, repair once
when permitted, and preserve service/data through failed preparation or rollback.

Publish release bundles with master images and expose an opt-in develop build
sharing the development index across Alpine and Debian images.

docker/armv6-run

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -eu
+export PROOT_NO_SECCOMP=1 QEMU_CPU=arm1176
+# Bind only kernel interfaces; all application files and writable state remain
+# inside this container's ARMv6 root. Child processes also pass through QEMU.
+exec proot -0 -q '/usr/bin/qemu-arm-static -cpu arm1176' \
+  -r /armv6 -b /proc -b /dev -w / "$@"