feat(core): 공통 UI 컴포넌트 및 상수 추가

## 새 파일

### AppDimensions (app_dimensions.dart)
- UI 관련 상수 중앙 집중화
- 패딩, 마진, 보더 레디우스, 아이콘 크기 등 정의
- 하드코딩된 값을 상수로 대체하여 일관성 확보

### InfoRow (info_row.dart)
- 레이블-값 쌍을 표시하는 공통 위젯
- 수평/수직 배치 지원

### SkeletonLoader (skeleton_loader.dart)
- Shimmer 효과를 가진 스켈레톤 로더
- RestaurantCardSkeleton, RestaurantListSkeleton 포함
- 로딩 상태 UX 개선

lib/core/constants/app_dimensions.dart

@@ -0,0 +1,55 @@
+/// UI 관련 상수 정의
+/// 하드코딩된 패딩, 마진, 크기 값들을 중앙 집중화
+class AppDimensions {
+  AppDimensions._();
+
+  // Padding & Margin
+  static const double paddingXs = 4.0;
+  static const double paddingSm = 8.0;
+  static const double paddingMd = 12.0;
+  static const double paddingDefault = 16.0;
+  static const double paddingLg = 20.0;
+  static const double paddingXl = 24.0;
+
+  // Border Radius
+  static const double radiusSm = 8.0;
+  static const double radiusMd = 12.0;
+  static const double radiusLg = 16.0;
+  static const double radiusXl = 20.0;
+  static const double radiusRound = 999.0;
+
+  // Icon Sizes
+  static const double iconSm = 16.0;
+  static const double iconMd = 24.0;
+  static const double iconLg = 32.0;
+  static const double iconXl = 48.0;
+  static const double iconXxl = 64.0;
+  static const double iconHuge = 80.0;
+
+  // Card Sizes
+  static const double cardIconSize = 48.0;
+  static const double cardMinHeight = 80.0;
+
+  // Ad Settings
+  static const int adInterval = 6; // 5리스트 후 1광고
+  static const int adOffset = 5; // 광고 시작 위치
+  static const double adHeightSmall = 100.0;
+  static const double adHeightMedium = 320.0;
+
+  // Distance Settings
+  static const double maxSearchDistance = 2000.0; // meters
+  static const int distanceSliderDivisions = 19;
+
+  // List Settings
+  static const double listItemSpacing = 8.0;
+  static const double sectionSpacing = 16.0;
+
+  // Bottom Sheet
+  static const double bottomSheetHandleWidth = 40.0;
+  static const double bottomSheetHandleHeight = 4.0;
+
+  // Avatar/Profile
+  static const double avatarSm = 32.0;
+  static const double avatarMd = 48.0;
+  static const double avatarLg = 64.0;
+}

lib/core/widgets/info_row.dart

@@ -0,0 +1,58 @@
+import 'package:flutter/material.dart';
+import '../constants/app_dimensions.dart';
+import '../constants/app_typography.dart';
+
+/// 상세 정보를 표시하는 공통 행 위젯
+/// [label]과 [value]를 수직 또는 수평으로 배치
+class InfoRow extends StatelessWidget {
+  final String label;
+  final String value;
+  final bool isDark;
+
+  /// true: 수평 배치 (레이블 | 값), false: 수직 배치 (레이블 위, 값 아래)
+  final bool horizontal;
+
+  /// 수평 배치 시 레이블 영역 너비
+  final double? labelWidth;
+
+  const InfoRow({
+    super.key,
+    required this.label,
+    required this.value,
+    required this.isDark,
+    this.horizontal = false,
+    this.labelWidth = 80,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    if (horizontal) {
+      return Padding(
+        padding: const EdgeInsets.symmetric(vertical: AppDimensions.paddingXs),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            SizedBox(
+              width: labelWidth,
+              child: Text(label, style: AppTypography.caption(isDark)),
+            ),
+            const SizedBox(width: AppDimensions.paddingSm),
+            Expanded(child: Text(value, style: AppTypography.body2(isDark))),
+          ],
+        ),
+      );
+    }
+
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: AppDimensions.paddingXs),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Text(label, style: AppTypography.caption(isDark)),
+          const SizedBox(height: 2),
+          Text(value, style: AppTypography.body2(isDark)),
+        ],
+      ),
+    );
+  }
+}

lib/core/widgets/skeleton_loader.dart

@@ -0,0 +1,147 @@
+import 'package:flutter/material.dart';
+import '../constants/app_colors.dart';
+import '../constants/app_dimensions.dart';
+
+/// Shimmer 효과를 가진 스켈톤 로더
+class SkeletonLoader extends StatefulWidget {
+  final double width;
+  final double height;
+  final double borderRadius;
+
+  const SkeletonLoader({
+    super.key,
+    this.width = double.infinity,
+    required this.height,
+    this.borderRadius = AppDimensions.radiusSm,
+  });
+
+  @override
+  State<SkeletonLoader> createState() => _SkeletonLoaderState();
+}
+
+class _SkeletonLoaderState extends State<SkeletonLoader>
+    with SingleTickerProviderStateMixin {
+  late AnimationController _controller;
+  late Animation<double> _animation;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      duration: const Duration(milliseconds: 1500),
+      vsync: this,
+    )..repeat();
+
+    _animation = Tween<double>(begin: -1.0, end: 2.0).animate(
+      CurvedAnimation(parent: _controller, curve: Curves.easeInOutSine),
+    );
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final isDark = Theme.of(context).brightness == Brightness.dark;
+    final baseColor = isDark
+        ? AppColors.darkSurface.withValues(alpha: 0.6)
+        : Colors.grey.shade300;
+    final highlightColor = isDark
+        ? AppColors.darkSurface.withValues(alpha: 0.9)
+        : Colors.grey.shade100;
+
+    return AnimatedBuilder(
+      animation: _animation,
+      builder: (context, child) {
+        return Container(
+          width: widget.width,
+          height: widget.height,
+          decoration: BoxDecoration(
+            borderRadius: BorderRadius.circular(widget.borderRadius),
+            gradient: LinearGradient(
+              begin: Alignment.centerLeft,
+              end: Alignment.centerRight,
+              colors: [baseColor, highlightColor, baseColor],
+              stops: [
+                (_animation.value - 1).clamp(0.0, 1.0),
+                _animation.value.clamp(0.0, 1.0),
+                (_animation.value + 1).clamp(0.0, 1.0),
+              ],
+            ),
+          ),
+        );
+      },
+    );
+  }
+}
+
+/// 맛집 카드 스켈톤
+class RestaurantCardSkeleton extends StatelessWidget {
+  const RestaurantCardSkeleton({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final isDark = Theme.of(context).brightness == Brightness.dark;
+
+    return Card(
+      margin: const EdgeInsets.symmetric(
+        horizontal: AppDimensions.paddingDefault,
+        vertical: AppDimensions.paddingSm,
+      ),
+      color: isDark ? AppColors.darkSurface : AppColors.lightSurface,
+      child: Padding(
+        padding: const EdgeInsets.all(AppDimensions.paddingDefault),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Row(
+              children: [
+                // 카테고리 아이콘 영역
+                const SkeletonLoader(
+                  width: AppDimensions.cardIconSize,
+                  height: AppDimensions.cardIconSize,
+                ),
+                const SizedBox(width: AppDimensions.paddingMd),
+                // 가게 정보 영역
+                Expanded(
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      const SkeletonLoader(height: 20, width: 150),
+                      const SizedBox(height: AppDimensions.paddingXs),
+                      const SkeletonLoader(height: 14, width: 100),
+                    ],
+                  ),
+                ),
+                // 거리 배지
+                const SkeletonLoader(width: 60, height: 28, borderRadius: 14),
+              ],
+            ),
+            const SizedBox(height: AppDimensions.paddingMd),
+            // 주소
+            const SkeletonLoader(height: 14),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// 맛집 리스트 스켈톤
+class RestaurantListSkeleton extends StatelessWidget {
+  final int itemCount;
+
+  const RestaurantListSkeleton({super.key, this.itemCount = 5});
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView.builder(
+      physics: const NeverScrollableScrollPhysics(),
+      itemCount: itemCount,
+      itemBuilder: (context, index) => const RestaurantCardSkeleton(),
+    );
+  }
+}