Aggregate per-entity update messages into S2CEntityUpdateBatch and
broadcast once per tick. Reuse serialized packets in several broadcast
loops to avoid repeated make_packet calls.
Add a Gait component synchronized over the network and procedural animation for model nodes. Load animation parameters from assets/model/creature/pig/animation.json and apply leg swing, body bob, and head motion based on gait. Refactor Gait into its own header for reuse.
Move direction into the transform component and include it in server-to-client entity updates. Client now sets transform direction from the network message and uses it to compute yaw for model rotation, so entities visually face their movement direction. Refactor net_utils to support arbitrary Vec3 fields.
Extend the network protocol with `C2SEntityCreateRequest` and `C2SEntityDestoryRequest` packets. Refactor entity managers to split public client-facing create/destroy methods that send requests over the network, from internal handlers that process received packets. Add utility functions for converting protobuf Vec3 to glm::vec3.
