docs: record DataPacket ownership model and lifecycle changes

- networking.md: add PacketFraming ctor overload, Ownership rules (5 rules), Outbound construction convention; rewrite Send (World) for the serialize-at-enqueue model; rewrite Receive (World) for the framing-mode branch split; drop stale IN PROGRESS / KNOWN LIMITATION warnings

- in_progress.md: mark DataPacket framing design STABILIZED with the ownership-rules summary; mark span API rollout DONE

- packets.md: add Outbound construction convention pointing at the outbound ctor + WriteBytes(proto, 4) pattern and flag the hand-rolled byte[] + inbound ctor anti-pattern

- tasks.md: update QueuedPacket shape (Owner, Wire, PacketId, PayloadLength) and describe the SendWire broadcast fast path

- entities.md: note Entity.Interaction is now an InteractionState POCO