feat(backend): Go 服务骨架（配置、日志、数据库、中间件、Wire）

- config: Viper YAML 配置 + 环境变量覆盖
- logs: zap 结构化日志 + trace_id 链路追踪 + 敏感信息脱敏
- db: PostgreSQL (GORM) + Redis (go-redis) 连接管理
- middleware: Trace/Logger/CORS/Recovery 四层中间件
- provider: Wire 编译时依赖注入
- main.go: 优雅启动/关闭 HTTP 服务

Made-with: Cursor

backend/go-service/cmd/server/main.go

@@ -0,0 +1,101 @@
+// Package main 是 EchoChat 后端服务的入口
+package main
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/echochat/backend/config"
+	"github.com/echochat/backend/pkg/logs"
+	"github.com/echochat/backend/pkg/middleware"
+	"github.com/echochat/backend/pkg/utils"
+	"github.com/echochat/backend/app/provider"
+	"github.com/gin-gonic/gin"
+	"go.uber.org/zap"
+)
+
+func main() {
+	// 1. 加载配置
+	cfg, err := config.Load("config", "config.dev")
+	if err != nil {
+		fmt.Printf("加载配置失败: %v\n", err)
+		os.Exit(1)
+	}
+
+	// 2. 初始化日志系统
+	if err := logs.Init(cfg.Log.Level, cfg.Log.Format, cfg.Log.OutputPath); err != nil {
+		fmt.Printf("初始化日志失败: %v\n", err)
+		os.Exit(1)
+	}
+	defer logs.Sync()
+
+	ctx := context.Background()
+	logs.Info(ctx, "main", "EchoChat 服务启动中",
+		zap.String("mode", cfg.Server.Mode),
+		zap.Int("port", cfg.Server.Port),
+	)
+
+	// 3. 通过 Wire 初始化所有组件
+	app, err := provider.InitializeApp(cfg)
+	if err != nil {
+		logs.Fatal(ctx, "main", "初始化应用失败", zap.Error(err))
+	}
+	_ = app
+
+	// 4. 创建 Gin Engine
+	if cfg.Server.Mode == "release" {
+		gin.SetMode(gin.ReleaseMode)
+	}
+	engine := gin.New()
+
+	// 5. 注册中间件（顺序：Trace → Logger → CORS → Recovery）
+	engine.Use(
+		middleware.Trace(),
+		middleware.Logger(),
+		middleware.CORS(),
+		middleware.Recovery(),
+	)
+
+	// 6. 注册路由
+	engine.GET("/health", func(c *gin.Context) {
+		utils.ResponseOK(c, gin.H{
+			"status":  "ok",
+			"service": "echochat",
+			"time":    time.Now().Format("2006-01-02 15:04:05"),
+		})
+	})
+
+	// 7. 启动 HTTP 服务（优雅关闭）
+	addr := fmt.Sprintf(":%d", cfg.Server.Port)
+	srv := &http.Server{
+		Addr:    addr,
+		Handler: engine,
+	}
+
+	go func() {
+		logs.Info(ctx, "main", "HTTP 服务启动", zap.String("addr", addr))
+		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			logs.Fatal(ctx, "main", "HTTP 服务启动失败", zap.Error(err))
+		}
+	}()
+
+	// 等待中断信号，优雅关闭
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
+	<-quit
+
+	logs.Info(ctx, "main", "正在关闭服务...")
+
+	shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+	if err := srv.Shutdown(shutdownCtx); err != nil {
+		logs.Error(ctx, "main", "服务关闭失败", zap.Error(err))
+	}
+
+	logs.Info(ctx, "main", "服务已停止")
+}