Lift the dictation + voice-conversation + auto-speak subsystem out of ChatBar
into composer/hooks/use-composer-voice.ts. It owns voiceConversationActive,
lastSpokenIdRef, the pending-reply readers, submitVoiceTurn, the voice
hooks (recorder/conversation/auto-speak), the Ctrl+B toggle event, and
handleToggleAutoSpeak; it exposes dictate/voiceStatus/voiceActivityState/
conversation/start+endConversation/handleToggleAutoSpeak for the controls.
Self-contained: consumes the draft/submit primitives (insertText, clearDraft,
focusInput, onSubmit) passed in, nothing depends back on it — so unlike the
queue subsystem (which is circularly coupled to the draft helpers) it lifts
cleanly. Behaviour-preserving; verbatim move.
cf05b38683