Two mirror-image bugs from voice/DM-call transitions leaving stale state.
DM call → space channel (stuck "Connecting…"):
The last participant to leave a DM call for a space channel receives a
`dm_call_ended` echo (server empties the DM room on their `voice_join`).
The handlers called `disconnectFn()` unconditionally, tearing down the
space room they had just connected to. Route `dm_call_ended` /
`dm_call_rejected` / terminal `dm_call_undeliverable` through a new
`teardownDmCall()` that only disconnects LiveKit when not in a space
channel (`currentVoiceChannelId` null).
Space channel → DM call (still shown as "in" the voice channel):
1. Entering a DM call never cleared `currentVoiceChannelId`, so
`VoiceChannel` mapped the DM call's live LiveKit participants onto the
old space channel. Add `clearSpaceVoiceForDmCall()`, called in
`connect()` when `isDm`, restoring the invariant that a DM call has no
`currentVoiceChannelId`.
2. `dm_call_accepted` gated the caller's connect on `!isLiveKitConnected`,
so a caller already in a space channel was never connected to the DM
room. Gate on `wasOutgoingCall` only (connect() de-dupes same-room).
Tests: teardownDmCall.test.ts, clearSpaceVoiceForDmCall.test.ts.
Docs: docs/systems/voice.md.
Jannis Braun
ac20f22c72