simplify: dedupe boilerplate and remove dead code across all layers

lib/view/pages/talk/data/chat_bubble_styles.dart

@@ -4,18 +4,6 @@ import '../../../../theming/app_theme.dart';
 import '../widgets/bubble.dart';
 
 extension ColorExtensions on Color {
-  Color invert() {
-    final invertedR = 1.0 - r;
-    final invertedG = 1.0 - g;
-    final invertedB = 1.0 - b;
-    return Color.from(
-      alpha: a,
-      red: invertedR,
-      green: invertedG,
-      blue: invertedB,
-    );
-  }
-
   Color withWhite(int whiteValue) {
     final value = whiteValue / 255.0;
     return Color.from(alpha: a, red: value, green: value, blue: value);

lib/view/pages/talk/data/chat_message.dart

@@ -16,8 +16,6 @@ class ChatMessage {
   RichObjectString? file;
   String content = '';
 
-  bool get containsFile => file != null;
-
   ChatMessage({required this.originalMessage, this.originalData}) {
     if (originalData?.containsKey('file') ?? false) {
       file = originalData?['file'];

lib/view/pages/talk/data/chat_search_controller.dart

@@ -10,6 +10,14 @@ class ChatSearchMatch {
 }
 
 class ChatSearchController {
+  /// System messages that are folded into other bubbles (reactions, poll
+  /// votes, deletions) and therefore never rendered nor searched as their own
+  /// entry.
+  static bool isHiddenSystemMessage(GetChatResponseObject element) =>
+      element.systemMessage.contains('reaction') ||
+      element.systemMessage.contains('poll_voted') ||
+      element.systemMessage.contains('message_deleted');
+
   static List<ChatSearchMatch> findMatches(
     GetChatResponse response,
     String query,
@@ -19,9 +27,7 @@ class ChatSearchController {
 
     final matches = <ChatSearchMatch>[];
     for (final element in response.sortByTimestamp()) {
-      if (element.systemMessage.contains('reaction')) continue;
-      if (element.systemMessage.contains('poll_voted')) continue;
-      if (element.systemMessage.contains('message_deleted')) continue;
+      if (isHiddenSystemMessage(element)) continue;
 
       final haystackText = RichObjectStringProcessor.parseToString(
         element.message,