🚀 feat: expose “Enabled Groups” for models with real-time refresh

Backend
• model/model_meta.go
  – Added `EnableGroups []string` to Model struct
  – fillModelExtra now populates EnableGroups

• model/model_groups.go
  – New helper `GetModelEnableGroups` (reuses Pricing cache)

• model/pricing_refresh.go
  – Added `RefreshPricing()` to force immediate cache rebuild

• controller/model_meta.go
  – `GetAllModelsMeta` & `SearchModelsMeta` call `model.RefreshPricing()` before querying, ensuring groups / endpoints are up-to-date

Frontend
• ModelsColumnDefs.js
  – Added `renderGroups` util and “可用分组” table column displaying color-coded tags

Result
Admins can now see which user groups can access each model, and any ability/group changes are reflected instantly without the previous 1-minute delay.

model/model_meta.go

@@ -38,6 +38,7 @@ type Model struct {
     DeletedAt   gorm.DeletedAt `json:"-" gorm:"index"`
 
     BoundChannels []BoundChannel `json:"bound_channels,omitempty" gorm:"-"`
+    EnableGroups []string       `json:"enable_groups,omitempty" gorm:"-"`
 }
 
 // Insert 创建新的模型元数据记录