Add bot-driven room app UI via im.paarrot.ui state.

Bots can publish a declarative panel UI that takes over a room; user
actions are sent as im.paarrot.ui.action timeline events.

src/app/utils/room.ts

@@ -24,6 +24,7 @@ import {
   Membership,
   MessageEvent,
   NotificationType,
+  PaarrotUiContent,
   RoomToParents,
   RoomType,
   StateEvent,
@@ -125,6 +126,33 @@ export const getPaarrotRoomKind = (room: Room | null): string | undefined => {
   return typeof kind === 'string' ? kind : undefined;
 };
 
+/**
+ * Valid bot-driven room UI state (im.paarrot.ui with version + root node).
+ */
+export const parsePaarrotUiContent = (raw: unknown): PaarrotUiContent | undefined => {
+  if (!raw || typeof raw !== 'object') return undefined;
+  const content = raw as PaarrotUiContent;
+  if (
+    typeof content.version !== 'number' ||
+    !content.root ||
+    typeof content.root !== 'object' ||
+    typeof content.root.type !== 'string' ||
+    typeof content.root.id !== 'string'
+  ) {
+    return undefined;
+  }
+  return content;
+};
+
+export const getPaarrotUiContent = (room: Room | null): PaarrotUiContent | undefined => {
+  if (!room) return undefined;
+  const event = room.currentState?.getStateEvents(StateEvent.PaarrotUi, '');
+  if (!event) return undefined;
+  return parsePaarrotUiContent(event.getContent());
+};
+
+export const hasRoomAppUi = (room: Room | null): boolean => getPaarrotUiContent(room) !== undefined;
+
 /**
  * m.forum space root (forum board lobby), not a plain m.space or a lone m.forum topic channel.
  * Matrix sets create type m.forum on forum spaces but SDK isSpaceRoom() is often still false;