Fix overlay: Directionality widget + startListening state guard

- Wrap overlay Stack with Directionality (required above MaterialApp)
- Guard startListening() for IncomingData/StaleData states to prevent
  overlay dismissal when status reloads on app resume

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mitra_app/lib/core/chat/widgets/chat_request_overlay.dart

@@ -79,9 +79,11 @@ class _ChatRequestOverlayState extends ConsumerState<ChatRequestOverlay>
       }
     });
 
-    return Stack(
-      children: [
-        widget.child,
+    return Directionality(
+      textDirection: TextDirection.ltr,
+      child: Stack(
+        children: [
+          widget.child,
         if (_visible) ...[
           // Semi-transparent dim
           Positioned.fill(
@@ -108,6 +110,7 @@ class _ChatRequestOverlayState extends ConsumerState<ChatRequestOverlay>
           ),
         ],
       ],
+      ),
     );
   }