refactor: 重构后端架构，采用 Go 风格四层设计模式

## 主要变更

### 🏗️ 架构重构
- 采用简洁的四层架构：API → Service → Repository → Model
- 遵循 Go 语言最佳实践和命名规范
- 实现依赖注入和接口导向设计
- 统一错误处理和响应格式

### 📁 目录结构优化
- 删除重复模块 (application/, domain/, infrastructure/ 等)
- 规范化命名 (使用 Go 风格的 snake_case)
- 清理无关文件 (package.json, node_modules/ 等)
- 新增规范化的测试目录结构

### 📚 文档系统
- 为每个模块创建详细的 CLAUDE.md 指导文件
- 包含开发规范、最佳实践和使用示例
- 支持模块化开发，缩短上下文长度

### 🔧 开发规范
- 统一接口命名规范 (UserServicer, PhotoRepositoryr)
- 标准化错误处理机制
- 完善的测试策略 (单元测试、集成测试、性能测试)
- 规范化的配置管理

### 🗂️ 新增文件
- cmd/server/ - 服务启动入口和配置
- internal/model/ - 数据模型层 (entity, dto, request)
- pkg/ - 共享工具包 (logger, response, validator)
- tests/ - 完整测试结构
- docs/ - API 文档和架构设计
- .gitignore - Git 忽略文件配置

### 🗑️ 清理内容
- 删除 Node.js 相关文件 (package.json, node_modules/)
- 移除重复的架构目录
- 清理临时文件和构建产物
- 删除重复的文档文件

## 影响
- 提高代码可维护性和可扩展性
- 统一开发规范，提升团队协作效率
- 优化项目结构，符合 Go 语言生态标准
- 完善文档体系，降低上手难度

backend/go.mod

@@ -1,29 +1,34 @@
 module photography-backend
 
-go 1.21
+go 1.23.0
+
+toolchain go1.24.4
 
 require (
-	github.com/gin-gonic/gin v1.9.1
+	github.com/gin-gonic/gin v1.10.1
 	github.com/golang-jwt/jwt/v5 v5.2.0
 	github.com/spf13/viper v1.18.2
 	go.uber.org/zap v1.26.0
-	golang.org/x/crypto v0.17.0
-	golang.org/x/text v0.14.0
+	golang.org/x/crypto v0.39.0
+	golang.org/x/text v0.26.0
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1
 	gorm.io/driver/postgres v1.5.4
-	gorm.io/gorm v1.25.5
+	gorm.io/gorm v1.30.0
 )
 
 require (
-	github.com/bytedance/sonic v1.9.1 // indirect
+	github.com/bytedance/sonic v1.13.3 // indirect
+	github.com/bytedance/sonic/loader v0.2.4 // indirect
 	github.com/chenzhuoyu/base64x v0.0.0-20221115062448-fe3a3abad311 // indirect
+	github.com/cloudwego/base64x v0.1.5 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
-	github.com/gabriel-vasile/mimetype v1.4.2 // indirect
-	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.9 // indirect
+	github.com/gin-contrib/cors v1.7.6 // indirect
+	github.com/gin-contrib/sse v1.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-playground/validator/v10 v10.14.0 // indirect
-	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/go-playground/validator/v10 v10.26.0 // indirect
+	github.com/goccy/go-json v0.10.5 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
@@ -32,14 +37,15 @@ require (
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
-	github.com/leodido/go-urn v1.2.4 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.10 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
-	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-sqlite3 v1.14.22 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
-	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
@@ -48,14 +54,15 @@ require (
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
-	github.com/ugorji/go/codec v1.2.11 // indirect
+	github.com/ugorji/go/codec v1.3.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	golang.org/x/arch v0.3.0 // indirect
+	golang.org/x/arch v0.18.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
-	golang.org/x/net v0.19.0 // indirect
-	golang.org/x/sync v0.5.0 // indirect
-	golang.org/x/sys v0.15.0 // indirect
-	google.golang.org/protobuf v1.31.0 // indirect
+	golang.org/x/net v0.41.0 // indirect
+	golang.org/x/sync v0.15.0 // indirect
+	golang.org/x/sys v0.33.0 // indirect
+	google.golang.org/protobuf v1.36.6 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gorm.io/driver/sqlite v1.6.0 // indirect
 )