perf(userfront): optimize login web loading

userfront/lib/core/i18n/locale_registry.dart

@@ -31,6 +31,22 @@ class LocaleRegistry {
   static final Set<String> _localeCodes = <String>{};
   static bool _initialized = false;
 
+  static void primeWithDefaults({
+    Iterable<String> localeCodes = const ['en', 'ko'],
+  }) {
+    if (_localeCodes.isNotEmpty) {
+      return;
+    }
+    _localeCodes.addAll(
+      localeCodes
+          .map((code) => code.toLowerCase().replaceAll('_', '-'))
+          .where(_isValidLocaleCode),
+    );
+    if (_localeCodes.isEmpty) {
+      _localeCodes.add(_safeFallbackLocaleCode);
+    }
+  }
+
   static Future<void> initialize({AssetBundle? assetBundle}) async {
     if (_initialized) {
       return;

userfront/lib/core/theme/app_theme.dart

@@ -42,11 +42,7 @@ ThemeData buildDarkTheme() {
 
 ThemeData _buildTheme(ColorScheme colorScheme) {
   final isDark = colorScheme.brightness == Brightness.dark;
-  final base = ThemeData(
-    useMaterial3: true,
-    colorScheme: colorScheme,
-    fontFamily: 'NotoSansKR',
-  );
+  final base = ThemeData(useMaterial3: true, colorScheme: colorScheme);
 
   return base.copyWith(
     scaffoldBackgroundColor: colorScheme.surfaceContainerLowest,

userfront/lib/main.dart

@@ -1,4 +1,5 @@
 // ignore_for_file: avoid_print
+import 'dart:async';
 import 'dart:convert';
 
 import 'package:flutter/foundation.dart';
@@ -7,7 +8,6 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:easy_localization/easy_localization.dart' hide tr;
 import 'package:go_router/go_router.dart';
-import 'package:flutter/services.dart';
 import 'package:flutter_web_plugins/flutter_web_plugins.dart';
 import 'features/auth/presentation/login_screen.dart';
 import 'features/auth/presentation/signup_screen.dart';
@@ -90,18 +90,6 @@ void _attemptRecoveryFromNullCheck({
   webWindow.redirectTo(target);
 }
 
-Future<void> _loadBundledFonts() async {
-  const family = 'NotoSansKR';
-  final loader = FontLoader(family);
-  try {
-    loader.addFont(rootBundle.load('assets/fonts/NotoSansKR-Regular.ttf'));
-    loader.addFont(rootBundle.load('assets/fonts/NotoSansKR-Bold.ttf'));
-    await loader.load();
-  } catch (e) {
-    _log.warning("Failed to preload bundled fonts: $e");
-  }
-}
-
 Future<void> _silentSessionRecovery() async {
   _log.info("[SessionRecovery] Starting silent session recovery check...");
 
@@ -165,11 +153,20 @@ Future<void> _silentSessionRecovery() async {
   }
 }
 
+bool _shouldRunStartupSessionRecovery(Uri uri) {
+  final requestedLocale = extractLocaleFromPath(uri);
+  if (requestedLocale == null) {
+    return true;
+  }
+  final path = stripLocalePath(uri);
+  return !isPublicAuthPath(path, uri);
+}
+
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   usePathUrlStrategy();
   await EasyLocalization.ensureInitialized();
-  await LocaleRegistry.initialize();
+  LocaleRegistry.primeWithDefaults();
 
   // 1. Global Error Handling
   FlutterError.onError = (details) {
@@ -201,14 +198,6 @@ void main() async {
 
   // 0. Initialize Logger
   LoggerService.init();
-  await ThemeController.app.restore();
-  await ThemeController.auth.restore();
-
-  // 폰트를 먼저 로딩해서 렌더링 깨짐(FOIT/FOUT) 최소화
-  await _loadBundledFonts();
-
-  // 2. Silent Session Recovery (from cookies)
-  await _silentSessionRecovery();
 
   runApp(
     // URL(/en, /ko)이 있으면 우선 적용해서 첫 렌더부터 올바른 언어로 시작합니다.
@@ -552,6 +541,12 @@ class _BaronSSOAppState extends State<BaronSSOApp> {
       // Re-run router redirects after the first frame so session-only web
       // storage state is reflected even when startup routing evaluated too early.
       AuthNotifier.instance.notify();
+      unawaited(LocaleRegistry.initialize());
+      unawaited(ThemeController.app.restore());
+      unawaited(ThemeController.auth.restore());
+      if (_shouldRunStartupSessionRecovery(Uri.base)) {
+        unawaited(_silentSessionRecovery());
+      }
     });
   }