0.3.0

Arete Widgets v0.3.0

Remove now retracts the widget's node from the realm.

Previously, removing a widget only forgot it in the app — the note said 'The
realm node is left as-is' — so every removal left a permanent participant
behind whose declarations still matched and could still be bound to. Remove
and Remove all now retract the node: its capabilities stop existing and the
substrate severs any connections that depended on them.

The realm half happens first. If retraction fails the widget is KEPT and you
are told why, so the app never loses the only local record of a node that
still exists on the realm. Because the SDK swallows server-side errors, the
result is verified against the realm rather than trusted, and removal refuses
to claim success when realm state cannot be seen.

The web app (PWA) has the same change.