#16940: fix(matrix): send voice messages as native voice bubbles

## Summary Voice messages were being sent as generic audio file attachments instead of native voice message bubbles in Matrix clients (Element, FluffyChat, etc.). ## Root Cause The `audioAsVoice` flag from `ReplyPayload` wasn't being passed through the outbound delivery chain to the Matrix adapter. The underlying `sendMessageMatrix` function already supports `audioAsVoice` and correctly sets `org.matrix.msc3245.voice: {}` when enabled. ## Changes 1. **`types.adapters.ts`**: Added `audioAsVoice?: boolean` to `ChannelOutboundContext` 2. **`deliver.ts`**: - Added `SendMediaOptions` type with `audioAsVoice` - Pass `audioAsVoice` in `sendMedia` calls 3. **`extensions/matrix/src/outbound.ts`**: Pass `audioAsVoice` to `sendMessageMatrix` ## Testing - When TTS is enabled or `asVoice: true` is set in the message tool, audio should now display as native voice message bubbles with waveform in Matrix clients. Fixes #14225 <!-- greptile_comment --> <h3>Greptile Summary</h3> Enables voice message bubbles in Matrix clients by threading `audioAsVoice` flag from `ReplyPayload` through the outbound delivery pipeline to the Matrix adapter. The changes properly add the `audioAsVoice` field to: - `ChannelOutboundContext` type with clear documentation - `SendMediaOptions` type for internal routing - The Matrix adapter's `sendMedia` call chain The underlying `sendMessageMatrix` function (extensions/matrix/src/matrix/send.ts:96) already supports `audioAsVoice` and correctly applies the MSC3245 voice message spec when enabled. Tests verify the voice message logic works correctly. One minor consistency improvement: the `sendPayload` handler should also pass `audioAsVoice` explicitly to the context (currently only available via `ctx.payload.audioAsVoice`). <h3>Confidence Score: 4/5</h3> - Safe to merge with minor style improvement suggested - The implementation correctly threads the `audioAsVoice` flag through the delivery pipeline. The underlying Matrix send logic already supports voice messages and has test coverage. One non-critical style improvement suggested for consistency in the `sendPayload` handler. - No files require special attention _{Last reviewed commit: 65c4884} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->