Voice mode: auto-submit on spacebar release (PTT send)

## Feature Request

### Summary
When using voice mode (push-to-talk with spacebar), automatically submit the transcribed text when the spacebar is released — without requiring a separate Enter key press.

### Current behavior
- Hold Space → records audio
- Release Space → transcription appears in input box
- User must press Enter manually to submit

### Desired behavior
- Hold Space → records audio
- Release Space → transcription appears **and is automatically submitted**

### Why
This would make the voice workflow fully hands-free. Currently the required Enter press breaks the flow, especially when the hands are away from the keyboard during dictation.

### Suggested implementation
Add a setting (e.g. \oice.autoSubmitOnRelease: true\) that sends Enter immediately after transcription is inserted on spacebar release.

Aucun fichier ni test n’est nommé. Commencez par localiser le gestionnaire de relâchement de la barre d’espace de voice-mode, le flux d’insertion de la transcription et le chemin de configuration d’un éventuel paramètre d’envoi automatique. C’est terminé lorsque l’audio push-to-talk relâché insère sa transcription et l’envoie automatiquement, tandis que le paramètre contrôle ce comportement.

Rédigé par le modèle d'indexation à partir du texte de l'issue.