feat: align RU validation, error contract, and generator runtime templates

Wire DSL-derived field labels, safe API error JSON (string|string[]), decimal/enum DTO fixes, and client dataProvider without comma-splitting. Add generation/templates/runtime as canonical source copied on generate; extend AID bundle, prompts, validation gate, and docs.

generation/templates/runtime/AppNotification.tsx

@@ -0,0 +1,16 @@
+import { Notification, NotificationProps } from 'react-admin';
+
+export const AppNotification = (props: NotificationProps) => (
+  <Notification
+    {...props}
+    sx={{
+      whiteSpace: 'pre-line',
+      '& .MuiAlert-message': {
+        whiteSpace: 'pre-line',
+      },
+      '& .MuiSnackbarContent-message': {
+        whiteSpace: 'pre-line',
+      },
+    }}
+  />
+);