feat: add vmux setup and vmux hook for Claude Code integration

- vmux setup: idempotently adds hooks to ~/.claude/settings.json
- vmux hook: receives Claude Code hook events via env vars and forwards to daemon
- Daemon handles "hook" action on Unix socket (no HTTP server needed)
- Hooks provide instant state detection (permission/question/idle)

daemon.go

@@ -452,6 +452,15 @@ func (d *Daemon) handleConnection(conn net.Conn) {
 		d.focus.Set(time.Duration(args.Minutes) * time.Minute)
 		writeResponse(conn, Response{OK: true, FocusRemaining: d.focus.Remaining().Minutes()})
 
+	case "hook":
+		var event HookEvent
+		if err := json.Unmarshal(req.Args, &event); err != nil {
+			writeResponse(conn, Response{Error: "invalid hook args: " + err.Error()})
+			return
+		}
+		d.processHookEvent(event)
+		writeResponse(conn, Response{OK: true})
+
 	case "stop":
 		writeResponse(conn, Response{OK: true})
 		d.Stop()