/api/v1/user/me 세션 시각을 추가하고 userfront 대시보드 Unknown 세션 시간 문제 수정

userfront/lib/features/dashboard/domain/session_time_resolver.dart

@@ -0,0 +1,50 @@
+import 'dart:convert';
+
+import '../../profile/data/models/user_profile_model.dart';
+
+DateTime? resolveDashboardSessionIssuedAt({
+  String? token,
+  UserProfile? profile,
+}) {
+  final tokenIssuedAt = _getJwtIssuedAt(token);
+  if (tokenIssuedAt != null) {
+    return tokenIssuedAt;
+  }
+  return _parseSessionAuthenticatedAt(profile?.sessionAuthenticatedAt);
+}
+
+DateTime? _getJwtIssuedAt(String? token) {
+  if (token == null || token.isEmpty) {
+    return null;
+  }
+  try {
+    final parts = token.split('.');
+    if (parts.length != 3) {
+      return null;
+    }
+    final payload = utf8.decode(
+      base64Url.decode(base64Url.normalize(parts[1])),
+    );
+    final data = json.decode(payload) as Map<String, dynamic>;
+    final iatValue = data['iat'] ?? data['auth_time'];
+    if (iatValue is num) {
+      return DateTime.fromMillisecondsSinceEpoch(
+        iatValue.toInt() * 1000,
+      ).toLocal();
+    }
+  } catch (_) {
+    return null;
+  }
+  return null;
+}
+
+DateTime? _parseSessionAuthenticatedAt(String? value) {
+  if (value == null || value.trim().isEmpty) {
+    return null;
+  }
+  try {
+    return DateTime.parse(value).toLocal();
+  } catch (_) {
+    return null;
+  }
+}