✨ feat: enhance model billing aggregation & UI display for unknown quota type

Summary
-------
1. **Backend**
   • `controller/model_meta.go`
     – For prefix/suffix/contains rules, aggregate endpoints, bound channels, enable groups, and quota types across all matched models.
     – When mixed billing types are detected, return `quota_type = -1` (unknown) instead of defaulting to volume-based.

2. **Frontend**
   • `web/src/helpers/utils.js`
     – `calculateModelPrice` now handles `quota_type = -1`, returning placeholder `'-'`.

   • `web/src/components/table/model-pricing/view/card/PricingCardView.jsx`
     – Billing tag logic updated: displays “按次计费” (times), “按量计费” (volume), or `'-'` for unknown.

   • `web/src/components/table/model-pricing/view/table/PricingTableColumns.js`
     – `renderQuotaType` shows “未知” for unknown billing type.

   • `web/src/components/table/models/ModelsColumnDefs.js`
     – Unified `renderQuotaType` to return `'-'` when type is unknown.

   • `web/src/components/table/model-pricing/modal/components/ModelPricingTable.jsx`
     – Group price table honors unknown billing type; pricing columns show `'-'` and neutral tag color.

3. **Utilities**
   • Added safe fallback colours/tags for unknown billing type across affected components.

Impact
------
• Ensures correct data aggregation for non-exact model matches.
• Prevents UI from implying volume billing when actual type is ambiguous.
• Provides consistent placeholder display (`'-'` or “未知”) across cards, tables and modals.

No breaking API changes; frontend gracefully handles legacy values.

web/src/components/table/models/ModelsColumnDefs.js

@@ -137,7 +137,8 @@ const renderQuotaType = (qt, t) => {
       </Tag>
     );
   }
-  return qt ?? '-';
+  // 未知
+  return '-';
 };
 
 // Render bound channels