Voice Transcription in Chat

Add the ability to transcribe text in the chat window similar to the ChatGPT app. This would allow users to speak their messages to the AI coach instead of typing, making the app more accessible and convenient to use, especially during workouts when hands may be occupied or sweaty. Key features: - Press-and-hold microphone button to record - Real-time speech-to-text transcription - Works seamlessly with the existing AI chat interface - Support for common fitness terminology