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/src/Serialization/SceneSerializer.cpp

@@ -306,7 +306,7 @@ namespace Engine::Serialization {
                 out << YAML::Key << "Friction" << YAML::Value << rb->friction;
                 out << YAML::Key << "Restitution" << YAML::Value
                     << rb->restitution;
-                out << YAML::Key << "IsSensor" << YAML::Value << rb->isSensor;
+                out << YAML::Key << "IsTrigger" << YAML::Value << rb->isTrigger;
                 // bodyId/bodyValid/velocity 由 PhysicsWorld 对账重建，不存
                 out << YAML::Key << "Active" << YAML::Value << rb->active;
                 out << YAML::EndMap;
@@ -616,7 +616,9 @@ namespace Engine::Serialization {
                 rb.gravityScale = n["GravityScale"].as<f32>(rb.gravityScale);
                 rb.friction = n["Friction"].as<f32>(rb.friction);
                 rb.restitution = n["Restitution"].as<f32>(rb.restitution);
-                rb.isSensor = n["IsSensor"].as<bool>(rb.isSensor);
+                // 新键 IsTrigger；旧场景 IsSensor 兼容读（缺键 as 返回 fallback 安全）
+                rb.isTrigger = n["IsTrigger"].as<bool>(
+                    n["IsSensor"].as<bool>(rb.isTrigger));
                 rb.active = n["Active"].as<bool>(true);
                 // bodyId/bodyValid/velocity 保持默认（对账重建）
             }