claude-code: drop what was removed while away, render one at a time, refuse an empty settings set

Review of the nox-mesh plugin: a watch hands over what is there, not what
went, so the view is pruned to the state's keys before it starts; the
watches and the tools render one at a time, as the home's record is read
and written whole; the register answer names how an item is offered.

modules/claude-code/cmd/claude-code/main.go

@@ -375,6 +375,15 @@ func main() {
 func run(p Paths, view *ServerView, configView *ConfigView) {
 	// The agent's configuration, at every scope (ADR 0216): the whole current set first, then each change.
 	go persist("watching the agent's configuration", func() error {
+		keys, err := stdio.State("config").Keys()
+		if err != nil {
+			return err
+		}
+		if configView.Prune(keys) {
+			if _, err := RenderNow(p, writeManaged); err != nil {
+				say("rendering after what was removed while away: %v", err)
+			}
+		}
 		return stdio.State("config").Watch("", func(c stdio.StateChange) error {
 			var item *Item
 			if c.Op == "put" {