physics: character controller (Jolt CharacterVirtual)

- CharacterControllerComponent: capsule params (radius/halfHeight, mass,
  max slope, step height); entity origin = feet via shape offset
- CharacterController per-entity wrapper: gravity integration + grounded
  clamp, ExtendedUpdate (sweep/slide + stick-to-floor + walk-stairs),
  SetLinearVelocity/Jump/IsGrounded facade
- PhysicsWorld: SyncCharacters reconcile (create/rebuild on param
  change, editor-drag teleport), UpdateCharacters after physics Update
  (Jolt recommended order), writes back to Transform
- Inspector: params + grounded/velocity telemetry + jump debug button
- Serialization: params only, state rebuilt by reconcile

Engine/src/Serialization/SceneSerializer.cpp

@@ -328,6 +328,21 @@ namespace Engine::Serialization {
                 out << YAML::EndMap;
             }
 
+            // 角色只存参数（速度/着地等状态不序列化）
+            if (const auto* cc = reg.try_get<ECS::CharacterControllerComponent>(e)) {
+                out << YAML::Key << "CharacterController" << YAML::Value
+                    << YAML::BeginMap;
+                out << YAML::Key << "Radius" << YAML::Value << cc->radius;
+                out << YAML::Key << "CapsuleHalfHeight" << YAML::Value
+                    << cc->capsuleHalfHeight;
+                out << YAML::Key << "Mass" << YAML::Value << cc->mass;
+                out << YAML::Key << "MaxSlopeAngle" << YAML::Value
+                    << cc->maxSlopeAngle;
+                out << YAML::Key << "StepHeight" << YAML::Value
+                    << cc->stepHeight;
+                out << YAML::EndMap;
+            }
+
             out << YAML::EndMap;   // Components
             out << YAML::EndMap;   // Entity
         }
@@ -601,6 +616,18 @@ namespace Engine::Serialization {
                 jc.limitMin = n["LimitMin"].as<f32>(jc.limitMin);
                 jc.limitMax = n["LimitMax"].as<f32>(jc.limitMax);
             }
+
+            if (const YAML::Node n = comps["CharacterController"]) {
+                auto& cc =
+                    handle.AddComponent<ECS::CharacterControllerComponent>();
+                cc.radius = n["Radius"].as<f32>(cc.radius);
+                cc.capsuleHalfHeight =
+                    n["CapsuleHalfHeight"].as<f32>(cc.capsuleHalfHeight);
+                cc.mass = n["Mass"].as<f32>(cc.mass);
+                cc.maxSlopeAngle = n["MaxSlopeAngle"].as<f32>(cc.maxSlopeAngle);
+                cc.stepHeight = n["StepHeight"].as<f32>(cc.stepHeight);
+                // 状态（速度/着地）由 PhysicsWorld 对账重建，不存
+            }
         }
 
         // 加载在 OnImGuiRender 段，错过本帧 UpdateTransforms：