Memory: StreamWriter uses an unbounded packet queue per client

[Tonguechaude]

Problem

StreamWriter holds a tokio::sync::mpsc::unbounded_channel for outgoing packets. Since this queue has no capacity limit, a client that reads slowly (laggy network, client freeze, slow loris) will cause the server to accumulate
Vec<u8> packet buffers indefinitely, one per encoded frame, with no backpressure and no eviction.

Under normal load this is invisible. Under load spikes (many particles, chunk sends, entity updates), a handful of slow clients can push RSS into the gigabyte range.

Expected behaviour

The server should apply backpressure or drop the connection (like limbo in hypixel) when a client cannot drain its outbound queue fast enough, rather than growing RAM without bound.

Notes

• The queue sits in src/net/runtime/src/connection.rs inside StreamWriter::new
• Each Vec<u8> in the queue is a compressed, encrypted packet ready to send, no further sharing, pure allocation pressure
• The issue is independent of game logic. It can be reproduced by throttling a client's TCP receive window