Reviewer flagged that constructing MessageEnvelope/DeliveryTask, minting
the messagingReqId, poking deliveryTask.msg.meta, and calling
sendService.send directly all reach past the messaging API into its
internals — a layer-boundary violation.
Replace that block in onReadyToSend with `await self.waku.send(envelope)`
where `envelope.meta` carries the wire-format marker. The channel now
holds a `Waku` instead of a `DeliveryService`. waku.send already handles
requestId generation, subscription, and DeliveryTask construction.
`waku.send` isn't `(raises: [])` so the await is wrapped in try/except to
keep the listener annotation honest.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
