Elephant Spawn Egg

Implement only these approved requirements: - Create an elephant as a passive custom entity using the fixed quadruped model. Apply defaults: width 0.9, height 1.4, health 20, movement speed 0.25, attack damage 2, armor 0, tracking range 8, pig sound family, passive default goals, and no natural spawning. - Create the elephant texture: A friendly gray elephant with large ears, a long trunk, and small white tusks, in a clean Minecraft-style pixel-art texture. - Create the elephant_spawn_egg texture: Minecraft-style spawn egg icon colored gray with ivory and muted blue speckles, representing an elephant.