Add voiceLanguage setting for /voice transcription

Feature Request

Problem

/voice mode always transcribes in English regardless of the spoken language. Users speaking Romanian (or any non-English language) get English transcriptions, which distorts the input.

Proposed Solution

Add a voiceLanguage setting to settings.json:

{
  "voiceLanguage": "ro"
}

This should pass the language code to the Whisper transcription model, which already supports 99 languages including Romanian.

Alternatives Considered

• Windows Speech Recognition language settings — doesn't influence Claude Code's transcription
• Speaking in the target language and hoping context is understood — works partially but unreliable

Use Case

Non-English speaking users (Romanian, Spanish, French, German, etc.) who want to use voice mode in their native language for faster interaction with Claude Code.

Environment

• Claude Code on Windows 11
• Voice mode enabled