✨ feat: Add model icon support across backend and UI; prefer model icon over vendor; add icon column in Models table

Backend:
- Model: Add `icon` field to `model.Model` (gorm: varchar(128)); auto-migrated via GORM.
- Pricing API: Extend `model.Pricing` with `icon` and populate from model meta in `GetPricing()`.

Frontend:
- EditModelModal: Add `icon` input (with @lobehub/icons helper link); wire into init/load/submit flows.
- ModelHeader / PricingCardView: Prefer rendering `model.icon`; fallback to `vendor_icon`; final fallback to initials avatar.
- Models table: Add leading “Icon” column, rendering `model.icon` or `vendor` icon via `getLobeHubIcon`.

Notes:
- Backward-compatible. Existing data without `icon` remain unaffected.
- No manual SQL needed; column is added by AutoMigrate.

Affected files:
- model/model_meta.go
- model/pricing.go
- web/src/components/table/models/modals/EditModelModal.jsx
- web/src/components/table/model-pricing/modal/components/ModelHeader.jsx
- web/src/components/table/model-pricing/view/card/PricingCardView.jsx
- web/src/components/table/models/ModelsColumnDefs.js

web/src/i18n/locales/en.json

@@ -1907,5 +1907,12 @@
   "确定要禁用所有的密钥吗？": "Are you sure you want to disable all keys?",
   "确定要删除所有已自动禁用的密钥吗？": "Are you sure you want to delete all automatically disabled keys?",
   "此操作不可撤销，将永久删除已自动禁用的密钥": "This operation cannot be undone, and all automatically disabled keys will be permanently deleted.",
-  "删除自动禁用密钥": "Delete auto disabled keys"
+  "删除自动禁用密钥": "Delete auto disabled keys",
+  "图标": "Icon",
+  "模型图标": "Model icon",
+  "请输入图标名称": "Please enter the icon name",
+  "精确名称匹配": "Exact name matching",
+  "前缀名称匹配": "Prefix name matching",
+  "后缀名称匹配": "Suffix name matching",
+  "包含名称匹配": "Contains name matching"
 }