implemented a customizable chat background system with support for patterns, solid colors, and gallery images; added a dedicated settings page with live preview and adjustable blur/dim effects, updated the image cropper to support flexible aspect ratios for wallpapers, and integrated file cleanup logic during account logout.

lib/storage/settings.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:json_annotation/json_annotation.dart';
 
+import 'chat_background_settings.dart';
 import 'dev_tools_settings.dart';
 import 'file_settings.dart';
 import 'file_view_settings.dart';
@@ -22,6 +23,7 @@ class Settings {
   ModulesSettings modulesSettings;
   TimetableSettings timetableSettings;
   TalkSettings talkSettings;
+  ChatBackgroundSettings chatBackgroundSettings;
   FileSettings fileSettings;
   HolidaysSettings holidaysSettings;
   FileViewSettings fileViewSettings;
@@ -35,6 +37,7 @@ class Settings {
     required this.modulesSettings,
     required this.timetableSettings,
     required this.talkSettings,
+    required this.chatBackgroundSettings,
     required this.fileSettings,
     required this.holidaysSettings,
     required this.fileViewSettings,