feat: Matrix login flow with auth guard and client provider

lib/core/matrix_client.dart

@@ -0,0 +1,30 @@
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+import 'package:matrix/matrix.dart';
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:sqflite_common_ffi/sqflite_ffi.dart';
+
+final matrixClientProvider = FutureProvider<Client>((ref) async {
+  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
+    sqfliteFfiInit();
+    databaseFactory = databaseFactoryFfi;
+  }
+
+  final appDir = await getApplicationSupportDirectory();
+  final dbPath = p.join(appDir.path, 'pyramid.sqlite');
+
+  final db = await databaseFactoryFfi.openDatabase(dbPath);
+  final sdkDb = await MatrixSdkDatabase.init('pyramid', database: db);
+
+  final client = Client('Pyramid', database: sdkDb);
+  await client.init();
+  return client;
+});
+
+final secureStorageProvider = Provider<FlutterSecureStorage>((ref) {
+  return const FlutterSecureStorage();
+});

lib/core/router.dart

@@ -1,14 +1,28 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
-import 'package:pyramid/layout/shell_page.dart';
-import 'package:pyramid/features/rooms/rooms_page.dart';
+import 'package:pyramid/features/auth/login_notifier.dart';
+import 'package:pyramid/features/auth/login_page.dart';
 import 'package:pyramid/features/chat/chat_page.dart';
+import 'package:pyramid/features/rooms/rooms_page.dart';
 import 'package:pyramid/features/settings/settings_page.dart';
+import 'package:pyramid/layout/shell_page.dart';
 
 final routerProvider = Provider<GoRouter>((ref) {
+  final isLoggedIn = ref.watch(isLoggedInProvider);
+
   return GoRouter(
     initialLocation: '/rooms',
+    redirect: (context, state) {
+      final loggingIn = state.matchedLocation == '/login';
+      if (!isLoggedIn && !loggingIn) return '/login';
+      if (isLoggedIn && loggingIn) return '/rooms';
+      return null;
+    },
     routes: [
+      GoRoute(
+        path: '/login',
+        builder: (context, state) => const LoginPage(),
+      ),
       ShellRoute(
         builder: (context, state, child) => ShellPage(child: child),
         routes: [