fix(mileage): 弹窗关闭改为向下滑出 + 淡出

- exit 从 y:60 改为 y:'100%'，整张表自顶向下滑出屏幕
- y/opacity 拆分 transition：y 走 spring，opacity 走 0.18s 淡出
- initial 也改为 y:'100%' 让出现/消失对称

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/mileage/VehicleDetailModal.tsx

@@ -118,10 +118,13 @@ export default function VehicleDetailModal({ vehicle, onClose }: Props) {
           onClick={onClose}
         >
           <motion.div
-            initial={{ y: 80, opacity: 0 }}
+            initial={{ y: '100%', opacity: 0 }}
             animate={{ y: 0, opacity: 1 }}
-            exit={{ y: 60, opacity: 0 }}
+            exit={{ y: '100%', opacity: 0 }}
-            transition={{ type: 'spring', damping: 28, stiffness: 320 }}
+            transition={{
+              y: { type: 'spring', damping: 32, stiffness: 320 },
+              opacity: { duration: 0.18 },
+            }}
             drag="y"
             dragControls={dragControls}
             dragListener={false}