feat(scheduling): add algorithm pure functions and export mapRegion

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/routes/vehicles.ts

@@ -91,7 +91,7 @@ WHERE truck.is_deleted = 0
 const REGIONS = ['嘉兴', '广东', '北京', '新疆', '其他'] as const;
 const INVENTORY_REGIONS = ['江浙沪', '广东', '新疆', '其它'] as const;
 
-function mapRegion(province: string | null, city: string | null): string {
+export function mapRegion(province: string | null, city: string | null): string {
   if (!province && !city) return '其他';
   const loc = (city || province || '').trim();
   if (loc.includes('嘉兴') || loc.includes('浙江') || loc.includes('上海') || loc.includes('江苏')) return '嘉兴';