feat(claude): add apiFormat support for provider presets

Allow preset providers to specify API format (anthropic or openai_chat),
enabling third-party proxy services that use OpenAI Chat Completions format.

src/components/providers/forms/ProviderForm.tsx

@@ -1139,6 +1139,14 @@ export function ProviderForm({
       preset.templateValues,
     );
 
+    // Sync preset's apiFormat to local state (for Claude providers)
+    if (preset.apiFormat) {
+      setLocalApiFormat(preset.apiFormat);
+    } else {
+      // Reset to default if preset doesn't specify apiFormat
+      setLocalApiFormat("anthropic");
+    }
+
     form.reset({
       name: preset.name,
       websiteUrl: preset.websiteUrl ?? "",

src/config/claudeProviderPresets.ts

@@ -43,6 +43,11 @@ export interface ProviderPreset {
   // 图标配置
   icon?: string; // 图标名称
   iconColor?: string; // 图标颜色
+
+  // Claude API 格式（仅 Claude 供应商使用）
+  // - "anthropic" (默认): Anthropic Messages API 格式，直接透传
+  // - "openai_chat": OpenAI Chat Completions 格式，需要格式转换
+  apiFormat?: "anthropic" | "openai_chat";
 }
 
 export const providerPresets: ProviderPreset[] = [