feat: sincronizar cor do tema via account data da conta Matrix

A cor escolhida no Appearance passa a ser guardada em im.fluffychat.account_config (primary_color), em vez de apenas nas preferencias locais do dispositivo.

- ApplicationAccountConfig ganha primaryColor, preservado em updateApplicationAccountConfig e no novo setApplicationAccountColor
- ThemeController restaura a cor da conta activa, aguarda accountDataLoading e reage a alteracoes remotas via onSync
- A cor final e derivada de _accountPrimaryColor ?? _localPrimaryColor, evitando corrida entre as preferencias locais e o sync
- Matrix notifica a troca de conta activa em initMatrix, setActiveClient e logout, corrigindo o indice do cliente activo
- Apagar o wallpaper preserva a cor; testes de serializacao do modelo

lib/pages/settings_style/settings_style.dart

@@ -10,6 +10,7 @@ import 'package:tatchat/utils/file_selector.dart';
 import 'package:tatchat/widgets/future_loading_dialog.dart';
 import 'package:tatchat/widgets/theme_builder.dart';
 import 'package:material_ui/material_ui.dart';
+import 'package:matrix/matrix.dart';
 
 import '../../widgets/matrix.dart';
 import 'settings_style_view.dart';
@@ -22,11 +23,18 @@ class SettingsStyle extends StatefulWidget {
 }
 
 class SettingsStyleController extends State<SettingsStyle> {
-  void setChatColor(Color? color) {
+  Future<void> setChatColor(Color? color) async {
+    final client = Matrix.of(context).client;
+    final themeController = ThemeController.of(context);
     AppSettings.colorSchemeSeedInt.setItem(
       color?.toARGB32() ?? AppSettings.colorSchemeSeedInt.defaultValue,
     );
-    ThemeController.of(context).setPrimaryColor(color);
+    await themeController.setPrimaryColor(color);
+    try {
+      await client.setApplicationAccountColor(color?.toARGB32());
+    } catch (e, s) {
+      Logs().e('Unable to save chat color', e, s);
+    }
   }
 
   Future<void> setWallpaper() async {
@@ -105,12 +113,19 @@ class SettingsStyleController extends State<SettingsStyle> {
     });
   }
 
-  void deleteChatWallpaper() => showFutureLoadingDialog(
-    context: context,
-    future: () => Matrix.of(context).client.setApplicationAccountConfig(
-      const ApplicationAccountConfig(wallpaperUrl: null, wallpaperBlur: null),
-    ),
-  );
+  void deleteChatWallpaper() {
+    final client = Matrix.of(context).client;
+    showFutureLoadingDialog(
+      context: context,
+      future: () => client.setApplicationAccountConfig(
+        ApplicationAccountConfig(
+          wallpaperUrl: null,
+          wallpaperBlur: null,
+          primaryColor: client.applicationAccountConfig.primaryColor,
+        ),
+      ),
+    );
+  }
 
   ThemeMode get currentTheme => ThemeController.of(context).themeMode;
   Color? get currentColor => ThemeController.of(context).primaryColor;