🚀 refactor: migrate vendor-count aggregation to model layer & align frontend logic

Summary
• Backend
  – Moved duplicate-name validation and total vendor-count aggregation from controllers (`controller/model_meta.go`, `controller/vendor_meta.go`, `controller/prefill_group.go`) to model layer (`model/model_meta.go`, `model/vendor_meta.go`, `model/prefill_group.go`).
  – Added `GetVendorModelCounts()` and `Is*NameDuplicated()` helpers; controllers now call these instead of duplicating queries.
  – API response for `/api/models` now returns `vendor_counts` with per-vendor totals across all pages, plus `all` summary.
  – Removed redundant checks and unused imports, eliminating `go vet` warnings.

• Frontend
  – `useModelsData.js` updated to consume backend-supplied `vendor_counts`, calculate the `all` total once, and drop legacy client-side counting logic.
  – Simplified initial data flow: first render now triggers only one models request.
  – Deleted obsolete `updateVendorCounts` helper and related comments.
  – Ensured search flow also sets `vendorCounts`, keeping tab badges accurate.

Why
This refactor enforces single-responsibility (aggregation in model layer), delivers consistent totals irrespective of pagination, and removes redundant client queries, leading to cleaner code and better performance.

controller/prefill_group.go

@@ -31,6 +31,15 @@ func CreatePrefillGroup(c *gin.Context) {
         common.ApiErrorMsg(c, "组名称和类型不能为空")
         return
     }
+    // 创建前检查名称
+    if dup, err := model.IsPrefillGroupNameDuplicated(0, g.Name); err != nil {
+        common.ApiError(c, err)
+        return
+    } else if dup {
+        common.ApiErrorMsg(c, "组名称已存在")
+        return
+    }
+
     if err := g.Insert(); err != nil {
         common.ApiError(c, err)
         return
@@ -49,6 +58,15 @@ func UpdatePrefillGroup(c *gin.Context) {
         common.ApiErrorMsg(c, "缺少组 ID")
         return
     }
+    // 名称冲突检查
+    if dup, err := model.IsPrefillGroupNameDuplicated(g.Id, g.Name); err != nil {
+        common.ApiError(c, err)
+        return
+    } else if dup {
+        common.ApiErrorMsg(c, "组名称已存在")
+        return
+    }
+
     if err := g.Update(); err != nil {
         common.ApiError(c, err)
         return