fix: separate server setup page, fix already-logged-in precondition error

lib/features/auth/login_notifier.dart

@@ -1,6 +1,20 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:matrix/matrix.dart';
 import 'package:pyramid/core/matrix_client.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+const _prefHomeserver = 'homeserver_url';
+
+// Gespeicherter Homeserver aus SharedPreferences
+final homeserverProvider = FutureProvider<String?>((ref) async {
+  final prefs = await SharedPreferences.getInstance();
+  return prefs.getString(_prefHomeserver);
+});
+
+Future<void> saveHomeserver(String url) async {
+  final prefs = await SharedPreferences.getInstance();
+  await prefs.setString(_prefHomeserver, url);
+}
 
 enum LoginStatus { idle, loading, error }
 
@@ -19,18 +33,17 @@ class LoginState {
 
 class LoginNotifier extends StateNotifier<LoginState> {
   final Ref _ref;
-
   LoginNotifier(this._ref) : super(const LoginState());
 
   Future<void> login({
-    required String userId,
+    required String username,
     required String password,
+    required String homeserver,
     String? deviceName,
   }) async {
     state = state.copyWith(status: LoginStatus.loading, errorMessage: null);
 
-    final clientAsync = _ref.read(matrixClientProvider);
-    final client = clientAsync.valueOrNull;
+    final client = _ref.read(matrixClientProvider).valueOrNull;
     if (client == null) {
       state = state.copyWith(
         status: LoginStatus.error,
@@ -39,20 +52,21 @@ class LoginNotifier extends StateNotifier<LoginState> {
       return;
     }
 
+    if (client.isLogged()) {
+      state = state.copyWith(status: LoginStatus.idle);
+      return;
+    }
+
     try {
-      // Auto-discover homeserver from MXID
-      if (userId.isValidMatrixId) {
-        final domain = Uri.https(userId.domain!, '');
-        try {
-          await client.checkHomeserver(domain);
-        } catch (_) {
-          client.homeserver = domain;
-        }
-      }
+      final serverUri = Uri.https(
+        homeserver.replaceAll(RegExp(r'^https?://'), ''),
+        '',
+      );
+      await client.checkHomeserver(serverUri);
 
       await client.login(
         LoginType.mLoginPassword,
-        identifier: AuthenticationUserIdentifier(user: userId),
+        identifier: AuthenticationUserIdentifier(user: username),
         password: password,
         initialDeviceDisplayName: deviceName ?? 'Pyramid',
       );