rendering: drive Run/Stand animations from actual movement state

CameraController now transitions the player character to Run (anim 4)
on movement start and back to Stand (anim 0) on stop, guarded by a
prevPlayerMoving_ flag so animation time is not reset every frame.
Death animation (anim 1) is never overridden.

Application creature sync similarly switches creature models to Run (4)
when they move between server positions and Stand (0) when they stop,
with per-guid creatureWasMoving_ tracking to avoid per-frame resets.

include/core/application.hpp

@@ -187,6 +187,7 @@ private:
     std::unordered_map<uint64_t, uint32_t> creatureInstances_;  // guid → render instanceId
     std::unordered_map<uint64_t, uint32_t> creatureModelIds_;   // guid → loaded modelId
     std::unordered_map<uint64_t, glm::vec3> creatureRenderPosCache_; // guid -> last synced render position
+    std::unordered_map<uint64_t, bool> creatureWasMoving_;       // guid -> previous-frame movement state
     std::unordered_set<uint64_t> creatureWeaponsAttached_;       // guid set when NPC virtual weapons attached
     std::unordered_map<uint64_t, uint8_t> creatureWeaponAttachAttempts_; // guid -> attach attempts
     std::unordered_map<uint32_t, bool> modelIdIsWolfLike_;     // modelId → cached wolf/worg check