v0.8.3

Added

• Plugins can send WhatsApp voice notes through ctx.conversations.send. A new voice envelope type sends the media at mediaUrl as a PTT voice note (audio bubble with waveform) rather than a plain audio file — the host maps it to an audio send with ptt set, which defaults the codec to audio/ogg; codecs=opus and classifies the message as voice, matching inbound classification. It rides the same conversation:send permission and activated-session scope as the other media types. (#607)