Add dedicated audio chat mode to ChatInput

[bdart]

This pull request introduces a new "audio mode" to the ChatInput component, allowing users to switch between text and audio input more seamlessly. It includes UI and logic updates to support entering, exiting, and managing the audio input state, as well as new tests and translation keys.

Audio Mode Feature Implementation:

• Added an isAudioMode state to ChatInput, toggled by a new handler, to control whether the user is in audio input mode. Entering audio mode hides the text area and dictation button, and shows an "Exit audio mode" button. Exiting audio mode stops any active recording and returns to text input. [1] [2] [3] [4] [5] [6] [7]

• The audio mode state is reset when a message is sent or when the component mode changes (e.g., switching from compose to edit). [1] [2]

Testing:

• Added tests to verify the correct UI and behavior when entering and exiting audio mode, including hiding/showing the text area, dictation button, and exit button, and ensuring recordings are properly stopped.

Internationalization:

• Added the "Exit audio mode" translation key to all supported languages. [1] [2] [3] [4] [5]

These changes improve the user experience for audio input in chat by making the mode switch explicit and user-friendly.