fix: 引擎使用传入的 _planner，不再内部 new DefaultDefensePlanner

- 构造函数传入的 planner 之前从未使用（死代码）
- Initialize 内删除了重复的 DB catalog 加载和 new DefaultDefensePlanner
- 现在统一由调用方注入 Planner

src/CounterDrone.Core/Simulation/SimulationEngine.cs

@@ -130,15 +130,8 @@ namespace CounterDrone.Core.Simulation
                 var threats = BuildDroneGroups(config);
                 if (fireUnits.Count > 0 && threats.Count > 0)
                 {
-                    using (var ammoDb = new SQLiteConnection(_paths.GetMainDbPath()))
-                    {
-                        var catalog = new List<AmmunitionSpec>(ammoDb.Table<AmmunitionSpec>().ToList());
-                        if (catalog.Count == 0)
-                            catalog = DefaultAmmunition.GetAll();
-                        var planner = new DefaultDefensePlanner(catalog);
-                        var result = planner.Plan(fireUnits, threats, _scene);
-                        SetFireSchedule(result.Best.MergedSchedule);
-                    }
+                    var result = _planner.Plan(fireUnits, threats, _scene);
+                    SetFireSchedule(result.Best.MergedSchedule);
                 }
             }