Implement connected/disconnected icon (vpn_key/vpn_key_off) in
both horizontal and vertical bar orientations. Right-click triggers
tailscale up / tailscale down via Process. Icon color follows
DMS theme (primary when connected, surfaceText when disconnected).
Closes#3
Minimal loadable DMS widget skeleton with plugin.json manifest
and TailscaleWidget.qml component. Symlinked, enabled, and loaded
cleanly in Dank Material Shell.
References #1, #2
