✨ feat: polish “Missing Models” UX & mobile actions layout

Overview
• Re-designed `MissingModelsModal` to align with `ModelTestModal` and deliver a cleaner, paginated experience.
• Improved mobile responsiveness for action buttons in `ModelsActions`.

Details
1. MissingModelsModal.jsx
   • Switched from `List` to `Table` for a more structured view.
   • Added search bar with live keyword filtering and clear icon.
   • Implemented pagination via `MODEL_TABLE_PAGE_SIZE`; auto-resets on search.
   • Dynamic rendering: when no data, show unified Empty state without column header.
   • Enhanced header layout with total-count subtitle and modal corner rounding.
   • Removed unused `Typography.Text` import.

2. ModelsActions.jsx
   • Set “Delete Selected Models” and “Missing Models” buttons to `flex-1 md:flex-initial`, placing them on the same row as “Add Model” on small screens.

Result
The “Missing Models” workflow now offers quicker discovery, a familiar table interface, and full mobile friendliness—without altering API behavior.

model/missing_models.go

@@ -0,0 +1,30 @@
+package model
+
+// GetMissingModels returns model names that are referenced in the system
+func GetMissingModels() ([]string, error) {
+    // 1. 获取所有已启用模型（去重）
+    models := GetEnabledModels()
+    if len(models) == 0 {
+        return []string{}, nil
+    }
+
+    // 2. 查询已有的元数据模型名
+    var existing []string
+    if err := DB.Model(&Model{}).Where("model_name IN ?", models).Pluck("model_name", &existing).Error; err != nil {
+        return nil, err
+    }
+
+    existingSet := make(map[string]struct{}, len(existing))
+    for _, e := range existing {
+        existingSet[e] = struct{}{}
+    }
+
+    // 3. 收集缺失模型
+    var missing []string
+    for _, name := range models {
+        if _, ok := existingSet[name]; !ok {
+            missing = append(missing, name)
+        }
+    }
+    return missing, nil
+}