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/components/retained-panel.tsx

@@ -0,0 +1,69 @@
+import { createContext, memo, type ReactNode, useContext } from "react";
+import { StyleSheet, View, type StyleProp, type ViewStyle } from "react-native";
+
+const RetainedPanelActiveContext = createContext(true);
+
+export function useRetainedPanelActive(): boolean {
+  return useContext(RetainedPanelActiveContext);
+}
+
+interface RetainedPanelProps {
+  active: boolean;
+  children: ReactNode;
+  style?: StyleProp<ViewStyle>;
+  testID?: string;
+}
+
+interface RetainedPanelActivityProps {
+  active: boolean;
+  children: ReactNode;
+}
+
+export function RetainedPanelActivity({ active, children }: RetainedPanelActivityProps) {
+  const parentActive = useRetainedPanelActive();
+  return (
+    <RetainedPanelActiveContext value={parentActive && active}>
+      {children}
+    </RetainedPanelActiveContext>
+  );
+}
+
+/**
+ * Keeps expensive panel state mounted without letting an inactive panel render
+ * on screen. The stable, non-collapsible native root is intentional: retained
+ * panels must not detach or reparent their native descendants when visibility
+ * changes.
+ */
+export const RetainedPanel = memo(function RetainedPanel({
+  active,
+  children,
+  style,
+  testID,
+}: RetainedPanelProps) {
+  const visibleStyle = StyleSheet.compose<ViewStyle, ViewStyle, ViewStyle>(styles.root, style);
+  const panelStyle = active
+    ? visibleStyle
+    : StyleSheet.compose<ViewStyle, ViewStyle, ViewStyle>(visibleStyle, styles.hidden);
+
+  return (
+    <RetainedPanelActivity active={active}>
+      <View
+        collapsable={false}
+        pointerEvents={active ? "auto" : "none"}
+        style={panelStyle}
+        testID={testID}
+      >
+        {children}
+      </View>
+    </RetainedPanelActivity>
+  );
+});
+
+const styles = StyleSheet.create({
+  root: {
+    flex: 1,
+  },
+  hidden: {
+    display: "none",
+  },
+});