Collapses the outgoing pipeline to `segmentation -> sds -> encryption ->
dispatch` by folding the encrypt-and-dispatch tail of `onReadyToSend`
directly into `send()`. Removes the `RateLimitManager` field, its
constructor param, the `ReadyToSendEvent` listener, and the
`awaitingDispatch` accounting that only existed to bridge the event-bus
hop between `send()` and `onReadyToSend`.
The `rate_limit_manager.nim` module itself is untouched — it will be
relocated to the messaging layer (co-located with RLN) in a follow-up
commit, where per-epoch admission actually belongs.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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