fix: resolve hydration mismatch error and improve project setup

- Fix React hydration mismatch in ThemeProvider with mounted state check
- Update layout.tsx to use light theme by default instead of system
- Optimize photo filtering with useMemo in page.tsx
- Add Express mock API for development
- Update CLAUDE.md with comprehensive project documentation
- Create backend/ and admin/ directories for future development

frontend/mock-api.js

@@ -0,0 +1,81 @@
+const express = require('express');
+const cors = require('cors');
+const app = express();
+
+app.use(cors());
+app.use(express.json());
+
+// 模拟照片数据
+const photos = [
+  {
+    id: 1,
+    src: '/placeholder.jpg',
+    title: '城市夜景',
+    description: '繁华都市中的宁静夜晚',
+    category: 'city',
+    tags: ['夜景', '城市', '建筑'],
+    date: '2024-01-15',
+    exif: {
+      camera: 'Canon EOS R5',
+      lens: '24-70mm f/2.8',
+      settings: 'f/4, 1/60s, ISO 800',
+      location: '上海外滩'
+    }
+  },
+  {
+    id: 2,
+    src: '/placeholder.jpg',
+    title: '自然风光',
+    description: '山川河流间的诗意景色',
+    category: 'nature',
+    tags: ['风景', '自然', '山水'],
+    date: '2024-01-10',
+    exif: {
+      camera: 'Sony A7R IV',
+      lens: '16-35mm f/2.8',
+      settings: 'f/8, 1/125s, ISO 200',
+      location: '张家界'
+    }
+  },
+  {
+    id: 3,
+    src: '/placeholder.jpg',
+    title: '人像摄影',
+    description: '捕捉真实的情感瞬间',
+    category: 'portrait',
+    tags: ['人像', '情感', '生活'],
+    date: '2024-01-05',
+    exif: {
+      camera: 'Nikon D850',
+      lens: '85mm f/1.4',
+      settings: 'f/2.8, 1/200s, ISO 400',
+      location: '工作室'
+    }
+  }
+];
+
+// 获取所有照片
+app.get('/api/photos', (req, res) => {
+  res.json(photos);
+});
+
+// 获取单张照片
+app.get('/api/photos/:id', (req, res) => {
+  const photo = photos.find(p => p.id === parseInt(req.params.id));
+  if (photo) {
+    res.json(photo);
+  } else {
+    res.status(404).json({ error: 'Photo not found' });
+  }
+});
+
+// 获取分类
+app.get('/api/categories', (req, res) => {
+  const categories = [...new Set(photos.map(p => p.category))];
+  res.json(categories);
+});
+
+const PORT = 3001;
+app.listen(PORT, () => {
+  console.log(`Mock API server running on http://localhost:${PORT}`);
+});