Add directly purchased cars to My Requests page

- Add new /my-vehicles API endpoint returning both recommended and direct purchases
- Add DirectPurchasedCarResponse and MyVehiclesResponse schemas
- Update frontend to display directly purchased cars (from banners with 1CC)
- Show separate collapsible section for direct purchases

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

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

backend/app/schemas/vehicle_request.py

@@ -123,3 +123,21 @@ class VehicleRequestWithVehicles(BaseModel):
 
     class Config:
         from_attributes = True
+
+
+# Directly purchased car (from CarView - when user pays 1CC on banner car)
+class DirectPurchasedCarResponse(BaseModel):
+    id: int  # CarView id
+    car_id: int
+    car_data: dict  # Car details for display
+    cc_paid: float
+    purchased_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+# Full response including both recommended and directly purchased cars
+class MyVehiclesResponse(BaseModel):
+    vehicle_requests: List[VehicleRequestWithVehicles]
+    direct_purchases: List[DirectPurchasedCarResponse]  # Cars purchased directly from banner