refactor(gameplay): integrate model and hitbox ID system into Entity

- Introduce HitboxID, EntityID, and ModelID types for safer ID-based lookups
- Replace AABB struct with Hitbox (includes HitboxID)
- Convert ModelManager and HitboxManager to singletons with Handle structs
- Update Entity to store IDs for model and hitbox, removing direct references
- Reorganize creature model assets into subdirectories per entity type
- Add player model (player.glb) and collision data for pig
- Remove ModelManager dependency from App and Renderer
- Add namespace parsing utility for asset paths
- Mark sparse_vector::insert() with [[nodiscard]]

src/gameplay/entity.cpp

@@ -1,6 +1,18 @@
 #include "Cubed/gameplay/entity.hpp"
 
+#include "Cubed/gameplay/hitbox_manager.hpp"
+#include "Cubed/render/model_manager.hpp"
 namespace Cubed {
+
+Entity::Entity(EntityID id, const std::string& name) {
+    m_info.id = id;
+    m_info.name = name;
+    auto h = ModelManager::model(name);
+    m_info.model = h.id;
+    auto b = HitboxManager::hitbox(name);
+    m_info.hitbox = b.id;
+}
+
 glm::vec3& Entity::max_speed() { return m_velocity.max; }
 float& Entity::acceleration() { return m_movement.acceleration; }
 float& Entity::deceleration() { return m_movement.deceleration; }
@@ -20,6 +32,7 @@ Movement& Entity::movement() { return m_movement; }
 Gravity& Entity::gravity() { return m_gravity; }
 MoveState& Entity::move_state() { return m_move_state; }
 Direction& Entity::direction() { return m_direction; }
+EntityInfo& Entity::info() { return m_info; }
 
 const Velocity& Entity::velocity() const { return m_velocity; }
 const Position& Entity::pos() const { return m_pos; }
@@ -29,5 +42,6 @@ const Movement& Entity::movement() const { return m_movement; }
 const Gravity& Entity::gravity() const { return m_gravity; }
 const MoveState& Entity::move_state() const { return m_move_state; }
 const Direction& Entity::direction() const { return m_direction; }
+const EntityInfo& Entity::info() const { return m_info; }
 
 } // namespace Cubed