feat: 数据概览/操作日志/批量操作 + 首页合格档案数

后台新增「数据概览」(商品/合格/按状态/品牌/分类/待审核) 与「操作日志」(全局审计分页)；商品列表支持多选批量改状态/分类。公开首页标题改为「天工」并展示合格档案数；新增公开接口 /api/v1/stats 与后台 /api/stats、/api/audit、/api/products/bulk。合格口径=quality_score≥0.6 且在用。

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

api/internal/handler/handler.go

@@ -26,6 +26,10 @@ var openAPISpec []byte
 // APIVersion is the current public API version prefix.
 const APIVersion = "v1"
 
+// QualifiedMinScore is the quality_score threshold at or above which a product
+// record is considered "qualified" (合格) for public stats.
+const QualifiedMinScore = 0.6
+
 const (
 	defaultPageSize = 20
 	maxPageSize     = 100
@@ -85,6 +89,7 @@ func (h *Handler) Router() http.Handler {
 			r.Get("/brands", h.ListBrands)
 			r.Get("/categories", h.ListCategories)
 			r.Get("/sources/{id}", h.SourceByID)
+			r.Get("/stats", h.Stats)
 		})
 	})
 
@@ -122,6 +127,15 @@ func (h *Handler) Healthz(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
 }
 
+// Stats returns catalog totals and the count of qualified records.
+func (h *Handler) Stats(w http.ResponseWriter, r *http.Request) {
+	st, err := h.store.Stats(r.Context(), QualifiedMinScore)
+	if h.handleErr(w, r, err) {
+		return
+	}
+	writeJSON(w, http.StatusOK, st)
+}
+
 // OpenAPI serves the embedded OpenAPI 3 specification for the public API.
 func (h *Handler) OpenAPI(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")