🔌 feat(api): extend endpoint type support & expose in pricing UI

* backend
  - constant/endpoint_type.go
    • Add EndpointTypeMidjourney, EndpointTypeSuno, EndpointTypeKling, EndpointTypeJimeng.
  - common/endpoint_type.go
    • Map Midjourney / MidjourneyPlus, SunoAPI, Kling, Jimeng channel types to the new endpoint types.

* frontend
  - ModelPricing.js
    • Add “Supported Endpoint Type” column.
    • Implement renderSupportedEndpoints with `stringToColor` for consistent tag colors.

These changes allow `/api/pricing` and model lists to return accurate
`supported_endpoint_types` covering all non-OpenAI providers and display
them clearly in the UI.

No breaking changes.

web/src/i18n/locales/en.json

@@ -1750,5 +1750,7 @@
   "批量创建时会在名称后自动添加随机后缀": "When creating in batches, a random suffix will be automatically added to the name",
   "额度必须大于0": "Quota must be greater than 0",
   "生成数量必须大于0": "Generation quantity must be greater than 0",
-  "创建后可在编辑渠道时获取上游模型列表": "After creation, you can get the upstream model list when editing the channel"
+  "创建后可在编辑渠道时获取上游模型列表": "After creation, you can get the upstream model list when editing the channel",
+  "可用端点类型": "Supported endpoint types",
+  "未登录，使用默认分组倍率：": "Not logged in, using default group ratio: "
 }