Add car_id field to RequestVehicle interface

- Add optional car_id field for linking to cars table
- Add regenerateSingle function to adminPdfApi

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -599,6 +599,7 @@ export interface VehicleRequest {
 export interface RequestVehicle {
   id: number;
   request_id: number;
+  car_id?: number;  // Reference to cars table
   car_data: Record<string, any>;
   is_approved: boolean;
   approved_at?: string;
@@ -1279,6 +1280,12 @@ export const adminPdfApi = {
     const { data } = await api.post('/carmodoo/admin/retry-all-failed-pdfs');
     return data;
   },
+
+  // 단일 차량 PDF 재생성
+  regenerateSingle: async (carId: number): Promise<{ message: string; pdf_path?: string }> => {
+    const { data } = await api.post(`/carmodoo/car/${carId}/regenerate-pdf`);
+    return data;
+  },
 };
 
 // Dashboard API