Client: Wire remote humans to dressed student proxies

[Kheartz]

StudentProxy gains a registry-free per-avatar API:

• SpawnProxy(x,y,z,yaw, Appearance, &skin) / DestroyProxy(actor)
• Appearance { bool female; int house; } selects the per-gender outfit and per-house tint/crest overlay (kit_params_houses.h)

human.cpp wiring (this is the Hogwarts stand-in for the native EntityFactory MafiaMP drives in its human.cpp):

• Create spawns a proxy at the entity's streamed Transform; the actor + GC-guard index + skin component live in a new Avatar component
• Update/UpdateRemoteHuman interpolate position and rotation and apply them via K2_TeleportTo; teleport-sized jumps snap instead of crawling
• Remove destroys the proxy
• Two fixes carried over from the broom work: read the local pawn's WORLD location via K2_GetActorLocation (RootComponent->RelativeLocation is parent-relative and stays static), and fetch Tracking only after all add()s so the player ref isn't written through a dangling archetype slot

Appearance is plumbed but defaults to Gryffindor male. Broom mount/dismount stays on broom_proxy and re-applies on top.