feat(provider): integrate icon system into provider UI components

Add icon customization support to provider management interface:

## Type System Updates

### Provider Interface (src/types.ts)
- Add optional `icon` field for icon name (e.g., "openai", "anthropic")
- Add optional `iconColor` field for hex color (e.g., "#00A67E")

### Form Schema (src/lib/schemas/provider.ts)
- Extend providerSchema with icon and iconColor optional fields
- Maintain backward compatibility with existing providers

## UI Components

### ProviderCard (src/components/providers/ProviderCard.tsx)
- Display ProviderIcon alongside provider name
- Add icon container with hover animation effect
- Adjust layout spacing for icon placement
- Update translate offsets for action buttons

### BasicFormFields (src/components/providers/forms/BasicFormFields.tsx)
- Add icon preview section showing current selection
- Implement fullscreen icon picker dialog
- Auto-apply default color from icon metadata on selection
- Display provider name and icon status in preview

### AddProviderDialog & EditProviderDialog
- Pass icon fields through form submission
- Preserve icon data during provider updates

This enables users to visually distinguish providers in the list
with custom icons, improving UX for multi-provider setups.

src/components/providers/EditProviderDialog.tsx

@@ -89,6 +89,8 @@ export function EditProviderDialog({
         notes: values.notes?.trim() || undefined,
         websiteUrl: values.websiteUrl?.trim() || undefined,
         settingsConfig: parsedConfig,
+        icon: values.icon?.trim() || undefined,
+        iconColor: values.iconColor?.trim() || undefined,
         ...(values.presetCategory ? { category: values.presetCategory } : {}),
         // 保留或更新 meta 字段
         ...(values.meta ? { meta: values.meta } : {}),
@@ -124,6 +126,8 @@ export function EditProviderDialog({
           settingsConfig: initialSettingsConfig,
           category: provider.category,
           meta: provider.meta,
+          icon: provider.icon,
+          iconColor: provider.iconColor,
         }}
         showButtons={false}
       />