* fix(server): pace routed output to its receiving client
A routed transfer previously waited only for the destination-to-intermediary write, so a slower final hop overflowed the route queue. Negotiate bounded per-channel acknowledgments after final forwarding drains, preserving concurrent small sends and legacy peers.
* fix(transport): keep small routed writes concurrent
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Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>