fix(scheduling): exclude near-qualified vehicles from rescue candidates

For rescue_hopeless (换走) scenario, filter out inventory candidates
where totalMileage/yearTarget >= 80%. These are already near target
and swapping them in adds no value.

Instead, prioritize candidates with biggest mileage gaps — they benefit
most from accumulating any mileage, even at a low-mileage customer.

Before: showed 粤AGR6869 (93% done, 缺口 1990) as "可达标" — pointless
After:  shows 浙FF58720 (0% done, 缺口 60000) — genuinely needs mileage

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

src/server/routes/scheduling/algorithm.ts

@@ -76,13 +76,21 @@ export function generateSuggestions(
   const suggestions: SchedulingSuggestion[] = [];
 
   // --- rescue_hopeless (high priority) ---
+  // For this scenario: take the hopeless car away to a high-mileage customer,
+  // and give the low-mileage customer a replacement from inventory.
+  // Exclude near-qualified candidates (completionRate >= 80%) — no point swapping
+  // in a car that's basically already at target.
+  // Instead, pick cars with BIG gaps: they benefit from any mileage, even at a low customer.
   for (const vehicle of hopeless) {
     const candidates: CandidateVehicle[] = inventoryVehicles
-      .filter(
-        (inv) =>
-          isTypeCompatible(vehicle.vehicleType, inv.vehicleType) &&
-          inv.region === vehicle.region,
-      )
+      .filter((inv) => {
+        if (!isTypeCompatible(vehicle.vehicleType, inv.vehicleType)) return false;
+        if (inv.region !== vehicle.region) return false;
+        // Exclude near-qualified: yearTarget known and already >= 80% done
+        const effectiveTarget = inv.yearTarget ?? vehicle.yearTarget;
+        if (effectiveTarget > 0 && inv.totalMileage / effectiveTarget >= 0.8) return false;
+        return true;
+      })
       .map((inv) => {
         const effectiveTarget = inv.yearTarget ?? vehicle.yearTarget;
         const mileageGap = Math.max(0, effectiveTarget - inv.totalMileage);
@@ -105,10 +113,8 @@ export function generateSuggestions(
         };
       })
       .sort((a, b) => {
-        if (a.canQualifyAfterSwap !== b.canQualifyAfterSwap)
-          return a.canQualifyAfterSwap ? -1 : 1;
-        // For hopeless: prefer already-qualified inventory, then highest completion
-        return b.completionRate - a.completionRate;
+        // Prefer biggest gap first — these benefit most from any mileage
+        return b.mileageGap - a.mileageGap;
       })
       .slice(0, 5);