✨ 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

model/model_meta.go

@@ -38,6 +38,7 @@ type Model struct {
     Id          int            `json:"id"`
     ModelName   string         `json:"model_name" gorm:"size:128;not null;uniqueIndex:uk_model_name,priority:1"`
     Description string         `json:"description,omitempty" gorm:"type:text"`
+    Icon        string         `json:"icon,omitempty" gorm:"type:varchar(128)"`
     Tags        string         `json:"tags,omitempty" gorm:"type:varchar(255)"`
     VendorID    int            `json:"vendor_id,omitempty" gorm:"index"`
     Endpoints   string         `json:"endpoints,omitempty" gorm:"type:text"`

model/pricing.go

@@ -16,6 +16,7 @@ import (
 type Pricing struct {
     ModelName              string                  `json:"model_name"`
     Description            string                  `json:"description,omitempty"`
+    Icon                   string                  `json:"icon,omitempty"`
     Tags                   string                  `json:"tags,omitempty"`
     VendorID               int                     `json:"vendor_id,omitempty"`
     QuotaType              int                     `json:"quota_type"`
@@ -272,6 +273,7 @@ func updatePricing() {
                 continue
             }
             pricing.Description = meta.Description
+            pricing.Icon = meta.Icon
             pricing.Tags = meta.Tags
             pricing.VendorID = meta.VendorID
         }