chore(init): 初始化解忧商行项目并完成 Phase 0 基座

backend/internal/modules/admindashboard/handler.go

@@ -0,0 +1,37 @@
+package admindashboard
+
+import (
+	"errors"
+	"net/http"
+
+	"hfb_sys/backend/pkg/response"
+
+	"github.com/gin-gonic/gin"
+)
+
+type Handler struct {
+	service *Service
+}
+
+func NewHandler(service *Service) *Handler {
+	return &Handler{service: service}
+}
+
+func (h *Handler) Summary(c *gin.Context) {
+	item, err := h.service.Summary(c.Request.Context())
+	if err != nil {
+		writeDashboardError(c, err)
+		return
+	}
+	response.OK(c, item)
+}
+
+func writeDashboardError(c *gin.Context, err error) {
+	response.RecordError(c, err)
+	switch {
+	case errors.Is(err, ErrDependencyUnavailable):
+		response.ServiceUnavailable(c, "数据库未连接")
+	default:
+		response.Error(c, http.StatusInternalServerError, "internal_error", "后台仪表盘服务暂时不可用")
+	}
+}