Refine Stage 4 runtime proxy management: introduce explicit lifecycle states (HeldNoRemote, HeldDisconnected, HeldLeftCell, Reusable, SpawnFailed), add a 30s disconnected-slot reuse delay, and implement per-slot hidden holding positions with spacing. Add a held-position correction pass (correct drift >25 units) and make disconnected-held slots become reusable after the grace period; reusable slots can be reassigned to later playerIds. Capture a remote player's current transform before performing the PlaceAtMe-backed Stage 4 spawn and apply that transform immediately when the isolated proxy is promoted, preventing a brief visual spawn near the local player. Misc: improved logging/throttling, slot assignment/reassignment logic, and various helper functions. Docs updated (architecture.md, dev-log.md) and plugin/src/F4TProxyActorController.cpp implements the behavior.