Entity replication for Pylon realtime shards.
A simulation keeps its replicated state in a [Replicated] store:
entities with stable u64 ids, a 3D position, and components (bytes in
the game's own encoding, keyed by a u8 id). Every change bumps the
store's change counter, so the server can tell what changed since it
last wrote to a given subscriber without diffing snapshots.
The server sends each subscriber replication frames ([frame]): spawn
(full state) for entities that came into view, update (only changed
axes and components) for entities in view, and despawn for entities
that left view. A client applies them to a [ReplicaTable].
A WebAssembly shard module records its store's changes
([Replicated::record_changes]) and hands them to the host each tick;
the host applies them to its copy ([Replicated::apply_changes]).
This crate has no dependencies, so guests build it for wasm32-unknown-unknown.