refactor: 重构后端架构为 go-zero 框架，优化项目结构

主要变更:
- 采用 go-zero 框架替代 Gin，提升开发效率
- 重构项目结构，API 文件模块化组织
- 将 model 移至 api/internal/model 目录
- 移除 common 包，改为标准 pkg 目录结构
- 实现统一的仓储模式，支持配置驱动数据库切换
- 简化测试策略，专注 API 集成测试
- 更新 CLAUDE.md 文档，提供详细的开发指导

技术栈更新:
- 框架: Gin → go-zero v1.6.0+
- 代码生成: 引入 goctl 工具
- 架构模式: 四层架构 → go-zero 三层架构 (Handler→Logic→Model)
- 项目布局: 遵循 Go 社区标准和 go-zero 最佳实践

backend/migrations/004_create_photos.sql

@@ -2,54 +2,63 @@
 
 CREATE TABLE photos (
     id SERIAL PRIMARY KEY,
-    title VARCHAR(255) NOT NULL,
+    title VARCHAR(200) NOT NULL,
     description TEXT,
     filename VARCHAR(255) NOT NULL,
-    file_path VARCHAR(500) NOT NULL,
+    original_url VARCHAR(500) NOT NULL,
+    thumbnail_url VARCHAR(500),
+    medium_url VARCHAR(500),
+    large_url VARCHAR(500),
     file_size BIGINT,
     mime_type VARCHAR(100),
     width INTEGER,
     height INTEGER,
-    category_id INTEGER REFERENCES categories(id),
-    exif JSONB,
+    camera_make VARCHAR(100),
+    camera_model VARCHAR(100),
+    lens_model VARCHAR(100),
+    focal_length DECIMAL(5,2),
+    aperture DECIMAL(3,1),
+    shutter_speed VARCHAR(20),
+    iso INTEGER,
     taken_at TIMESTAMP,
-    location VARCHAR(255),
+    location_name VARCHAR(200),
+    latitude DECIMAL(10,8),
+    longitude DECIMAL(11,8),
+    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    album_id INTEGER,
+    category_id INTEGER,
     is_public BOOLEAN DEFAULT true,
-    status VARCHAR(20) DEFAULT 'draft',
+    is_featured BOOLEAN DEFAULT false,
     view_count INTEGER DEFAULT 0,
     like_count INTEGER DEFAULT 0,
-    user_id INTEGER NOT NULL REFERENCES users(id),
+    download_count INTEGER DEFAULT 0,
+    sort_order INTEGER DEFAULT 0,
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     deleted_at TIMESTAMP
 );
 
--- 创建照片标签关联表
-CREATE TABLE photo_tags (
-    photo_id INTEGER REFERENCES photos(id) ON DELETE CASCADE,
-    tag_id INTEGER REFERENCES tags(id) ON DELETE CASCADE,
-    PRIMARY KEY (photo_id, tag_id)
-);
-
 -- 创建索引
-CREATE INDEX idx_photos_category_id ON photos(category_id);
 CREATE INDEX idx_photos_user_id ON photos(user_id);
-CREATE INDEX idx_photos_status ON photos(status);
+CREATE INDEX idx_photos_album_id ON photos(album_id);
+CREATE INDEX idx_photos_category_id ON photos(category_id);
 CREATE INDEX idx_photos_is_public ON photos(is_public);
+CREATE INDEX idx_photos_is_featured ON photos(is_featured);
 CREATE INDEX idx_photos_taken_at ON photos(taken_at);
 CREATE INDEX idx_photos_created_at ON photos(created_at);
 CREATE INDEX idx_photos_view_count ON photos(view_count);
 CREATE INDEX idx_photos_like_count ON photos(like_count);
-CREATE INDEX idx_photos_deleted_at ON photos(deleted_at);
+CREATE INDEX idx_photos_sort_order ON photos(sort_order);
+CREATE INDEX idx_photos_deleted_at ON photos(deleted_at) WHERE deleted_at IS NOT NULL;
 
--- 为JSONB字段创建GIN索引（支持高效的JSON查询）
-CREATE INDEX idx_photos_exif_gin ON photos USING GIN (exif);
+-- 地理位置索引
+CREATE INDEX idx_photos_location ON photos(latitude, longitude) WHERE latitude IS NOT NULL AND longitude IS NOT NULL;
 
--- 全文搜索索引
-CREATE INDEX idx_photos_title_gin ON photos USING GIN (to_tsvector('english', title));
-CREATE INDEX idx_photos_description_gin ON photos USING GIN (to_tsvector('english', description));
+-- 添加更新时间触发器
+CREATE TRIGGER update_photos_updated_at BEFORE UPDATE ON photos
+FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
 
 -- +migrate Down
 
-DROP TABLE IF EXISTS photo_tags;
+DROP TRIGGER IF EXISTS update_photos_updated_at ON photos;
 DROP TABLE IF EXISTS photos;