feat(app): stabilize recommendation flow

lib/presentation/providers/restaurant_provider.dart

@@ -1,5 +1,6 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:lunchpick/core/utils/category_mapper.dart';
+import 'package:lunchpick/core/utils/app_logger.dart';
 import 'package:lunchpick/domain/entities/restaurant.dart';
 import 'package:lunchpick/domain/repositories/restaurant_repository.dart';
 import 'package:lunchpick/presentation/providers/di_providers.dart';
@@ -14,16 +15,28 @@ final restaurantListProvider = StreamProvider<List<Restaurant>>((ref) {
 });
 
 /// 거리 정보를 포함한 맛집 목록 Provider (현재 위치 기반)
+/// StreamProvider 의존으로 초기 이벤트를 놓치는 문제를 피하기 위해
+/// 기존 리스트 스트림의 AsyncValue를 그대로 전달하며 정렬만 적용한다.
 final sortedRestaurantsByDistanceProvider =
-    StreamProvider<List<({Restaurant restaurant, double? distanceKm})>>((ref) {
-      final restaurantsStream = ref.watch(restaurantListProvider.stream);
-      final positionAsync = ref.watch(currentLocationProvider);
+    Provider<AsyncValue<List<({Restaurant restaurant, double? distanceKm})>>>((
+      ref,
+    ) {
+      final restaurantsAsync = ref.watch(restaurantListProvider);
+      final positionAsync = ref.watch(currentLocationWithFallbackProvider);
       final position = positionAsync.maybeWhen(
-        data: (pos) => pos ?? defaultPosition(),
+        data: (pos) => pos,
         orElse: () => defaultPosition(),
       );
 
-      return restaurantsStream.map((restaurants) {
+      AppLogger.debug(
+        '[restaurant_list] position ready for sorting: '
+        '${position.latitude}, ${position.longitude}',
+      );
+
+      return restaurantsAsync.whenData((restaurants) {
+        AppLogger.debug(
+          '[restaurant_list] incoming restaurants: ${restaurants.length}',
+        );
         final sorted =
             restaurants.map<({Restaurant restaurant, double? distanceKm})>((r) {
               final distanceKm = DistanceCalculator.calculateDistance(
@@ -38,6 +51,10 @@ final sortedRestaurantsByDistanceProvider =
                 b.distanceKm ?? double.infinity,
               ),
             );
+        AppLogger.debug(
+          '[restaurant_list] sorted list emitted, first distanceKm: '
+          '${sorted.isNotEmpty ? sorted.first.distanceKm?.toStringAsFixed(3) : 'none'}',
+        );
         return sorted;
       });
     });