Prevent Android chats from freezing or going blank (#1989)

* fix(app): stabilize streamed chat rendering

Use deterministic Markdown AST keys and preserve unique row identities when an assistant message resumes after a tool. Keep native gesture and plan-card children correctly keyed to avoid unsupported Fabric reconciliation paths.

* fix(app): stabilize retained native panels

Keep retained workspace roots in a stable native order and make active
panels present in the selection commit. Hidden panels now stop expensive
subscriptions and animations without losing mounted state.

* fix(app): harden retained panel activity

packages/app/src/agent-stream/turn-footer.tsx

@@ -35,18 +35,23 @@ export type AssistantTurnForkHandler = (input: {
 
 export const TurnFooter = memo(function TurnFooter({
   isRunning,
+  isActive,
   inFlightTurnStartedAt,
   host,
   strategy,
   onForkAssistantTurn,
 }: {
   isRunning: boolean;
+  isActive: boolean;
   inFlightTurnStartedAt: Date | null;
   host: TurnFooterHost | null;
   strategy: TurnContentStrategy;
   onForkAssistantTurn?: AssistantTurnForkHandler;
 }) {
   if (isRunning) {
+    if (!isActive) {
+      return null;
+    }
     return (
       <TurnFooterRow>
         <RunningTurnFooter inFlightTurnStartedAt={inFlightTurnStartedAt} />