perf: 毁伤判定加快速排斥 (距离>2R跳过PathInSphere)

密度检查提前到外层循环，减少不必要计算

src/CounterDrone.Core/Simulation/SimulationEngine.cs

@@ -275,22 +275,28 @@ namespace CounterDrone.Core.Simulation
                 }
             }
 
-            // 6. 毁伤判定：积分路径段在云内的时间
+            // 6. 毁伤判定：积分路径段在云内的时间（快速排斥：先检查包围盒）
             var (wvx, wvy, wvz) = Kinematics.WindToVector((WindDirection)_scene.WindDirection, (float)_scene.WindSpeed);
             float cloudDx = wvx * scaledDt, cloudDy = wvy * scaledDt, cloudDz = wvz * scaledDt;
+            float effectiveConcentration = (float)_ammoSpec.EffectiveConcentration;
             for (int di = 0; di < _flyingDrones.Count; di++)
             {
                 var drone = _flyingDrones[di];
                 for (int ci = 0; ci < _clouds.Count; ci++)
                 {
                     var cloud = _clouds[ci];
+                    if (cloud.Dispersion.CoreDensity < effectiveConcentration) continue;
+                    // 快速排斥：检查无人机与云团中心的距离是否在 2×有效半径内
+                    float effR = cloud.Dispersion.EffectiveRadius;
                     float ccx = cloud.Dispersion.Center.X, ccy = cloud.Dispersion.Center.Y, ccz = cloud.Dispersion.Center.Z;
+                    float dx = drone.PosX - ccx, dy = drone.PosY - ccy, dz = drone.PosZ - ccz;
+                    float distSq = dx * dx + dy * dy + dz * dz;
+                    if (distSq > effR * effR * 4) continue; // 距离 > 2R，不可能穿云
                     float inCloudDistance = DamageAssessment.PathInSphere(
                         drone.PrevX - (ccx - cloudDx), drone.PrevY - (ccy - cloudDy), drone.PrevZ - (ccz - cloudDz),
                         drone.PosX - ccx, drone.PosY - ccy, drone.PosZ - ccz,
-                        0f, 0f, 0f,
-                        cloud.Dispersion.EffectiveRadius);
-                    if (inCloudDistance > 0 && cloud.Dispersion.CoreDensity >= (float)_ammoSpec.EffectiveConcentration)
+                        0f, 0f, 0f, effR);
+                    if (inCloudDistance > 0)
                     {
                         float exposureIncrement = inCloudDistance / (drone.TypicalSpeed / 3.6f);
                         drone.ExposureTime += exposureIncrement;