refactor(scheduling): rewrite terminology to match core business logic

Core story: 里程高的车换下来，里程少的车换上去。

- Summary cards: "里程高·需换下" / "里程低·需换走" / "替换建议"
- List tags: "换下" (amber) / "换走" (blue) with matching color bars
- Detail modal title: "里程高·换下此车" / "里程低·换走此车"
- Candidate section: explains WHY these vehicles are recommended
  - 换下: "以下车辆里程缺口大，换到该高里程客户处可加速达标"
  - 换走: "以下车辆里程已充足，可调给当前客户，将此车换走给高里程客户冲刺"
- Reason text: states current situation + clear action recommendation
  with specific numbers (已跑, 缺口, 日均, 完成率)

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

src/server/routes/scheduling/algorithm.ts

@@ -3,6 +3,11 @@ import type {
   CandidateVehicle, VehicleClassification, SchedulingSummary,
 } from './types.js';
 
+function fmtKmSimple(v: number): string {
+  if (v >= 10000) return (v / 10000).toFixed(1) + '万';
+  return Math.round(v).toLocaleString();
+}
+
 // ---------------------------------------------------------------------------
 // 1. Vehicle type compatibility
 // ---------------------------------------------------------------------------
@@ -105,7 +110,10 @@ export function generateSuggestions(
       })
       .slice(0, 5);
 
-    const reason = `${vehicle.customer}日均里程仅 ${Math.round(vehicle.customerAvgDaily)} KM，该车达标概率 ${Math.round((vehicle.predictedYearEnd / vehicle.yearTarget) * 100)}%，建议替换为已达标车辆，将此车调配给高里程客户。`;
+    const yearRate = vehicle.yearTarget > 0 ? Math.round((vehicle.currentYearMileage / vehicle.yearTarget) * 100) : 0;
+    const gap = Math.max(0, vehicle.yearTarget - vehicle.currentYearMileage);
+    const reason = `该车在客户「${vehicle.customer}」处日均仅 ${Math.round(vehicle.customerAvgDaily)} km，本年完成率 ${yearRate}%，还差 ${fmtKmSimple(gap)} km 达标，按当前速度年底无法完成。`
+      + `\n建议：将此车调配给高里程客户冲刺达标，同时从库存调一辆已达标的车给当前客户。`;
 
     suggestions.push({
       id: `hopeless-${vehicle.plateNumber}`,
@@ -156,7 +164,8 @@ export function generateSuggestions(
       .slice(0, 5);
 
     const yearRate = vehicle.yearTarget > 0 ? Math.round((vehicle.currentYearMileage / vehicle.yearTarget) * 100) : 0;
-    const reason = `${vehicle.customer}日均里程 ${Math.round(vehicle.customerAvgDaily)} KM（高里程），该车本年完成率 ${yearRate}%，建议换上里程缺口大的车辆以加速达标。`;
+    const reason = `该车在客户「${vehicle.customer}」处已达标（完成率 ${yearRate}%），客户日均 ${Math.round(vehicle.customerAvgDaily)} km，属于高里程客户。`
+      + `\n建议：将此车换下，换上一辆里程少的车，利用该客户的高日均里程帮助新车快速达标。`;
 
     suggestions.push({
       id: `qualified-${vehicle.plateNumber}`,