Add versioned system dir, /opt/dockside.img staging, and rsync entrypoint upgrade#30

struanb wants to merge 3 commits intomainnewsnowlabs/dockside:mainfrom

claude/versioned-system-rsync-P3IUonewsnowlabs/dockside:claude/versioned-system-rsync-P3IUoCopy head branch name to clipboard