Cleaned up code, implemented message queue to notify subscribers of document updates.

lib/core/widgets/material/search/m3_search.dart

@@ -4,6 +4,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 
 /// Shows a full screen search page and returns the search result selected by
 /// the user when the page is closed.
@@ -221,12 +222,13 @@ abstract class SearchDelegate<T> {
     final ColorScheme colorScheme = theme.colorScheme;
     return theme.copyWith(
       appBarTheme: AppBarTheme(
-        brightness: colorScheme.brightness,
+        systemOverlayStyle: colorScheme.brightness == Brightness.light
+            ? SystemUiOverlayStyle.light
+            : SystemUiOverlayStyle.dark,
         backgroundColor: colorScheme.brightness == Brightness.dark
             ? Colors.grey[900]
             : Colors.white,
         iconTheme: theme.primaryIconTheme.copyWith(color: Colors.grey),
-        textTheme: theme.textTheme,
       ),
       inputDecorationTheme: searchFieldDecorationTheme ??
           InputDecorationTheme(

lib/core/widgets/shimmer_placeholder.dart

@@ -0,0 +1,21 @@
+import 'package:flutter/material.dart';
+import 'package:shimmer/shimmer.dart';
+
+class ShimmerPlaceholder extends StatelessWidget {
+  final Widget child;
+
+  const ShimmerPlaceholder({super.key, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Shimmer.fromColors(
+      baseColor: Theme.of(context).brightness == Brightness.light
+          ? Colors.grey[300]!
+          : Colors.grey[900]!,
+      highlightColor: Theme.of(context).brightness == Brightness.light
+          ? Colors.grey[100]!
+          : Colors.grey[600]!,
+      child: child,
+    );
+  }
+}