refactor(physics): rename isSensor to isTrigger (Unity/UE terminology)

UE calls it Trigger (Overlap Events / Trigger preset) and Unity's UI
says "Is Trigger"; "sensor" is the physics-backend term (Jolt sensor,
Box2D sensor). Rename the component/record flag and the Inspector
label. Scene files now persist "IsTrigger" with backward-compatible
read of the old "IsSensor" key.

Engine/include/Engine/ECS/Components.h

@@ -232,8 +232,9 @@ namespace Engine::ECS {
         f32 friction = 0.5f;
         f32 restitution = 0.2f;
 
-        // 传感器（Unity isTrigger 语义）：只产生 Added/Removed 事件，无碰撞解算
-        bool isSensor = false;
+        // 触发器（Unity isTrigger / UE Overlap Events 语义）：只产生
+        // Added/Removed 事件，无碰撞解算；底层 Jolt sensor
+        bool isTrigger = false;
 
         // 运行时（PhysicsWorld 维护，勿手改）
         u32 bodyId = 0;          // JPH::BodyID 裸位

Engine/include/Engine/Physics/PhysicsWorld.h

@@ -110,7 +110,7 @@ namespace Engine {
             f32 halfHeight = 0.0f;        // Capsule/Cylinder 圆柱段半高
             std::vector<ECS::RigidBodyComponent::CompoundChild> compound; // 子形状快照
             f32 mass = 0.0f;
-            bool isSensor = false;       // 传感器标记（变更 → 重建 body）
+            bool isTrigger = false;      // 触发器标记（变更 → 重建 body）
             glm::vec3 lastPos{0.0f};     // 静态/运动体编辑器拖动检测
             glm::quat lastRot{1.0f, 0.0f, 0.0f, 0.0f};   // 同上（quat 直比，无欧拉往返）
             // 加速度箭头用：上一步速度（定步长差分）与平滑后的加速度