Add Model Download Notification and Display Language Toast with AI Settings Prompt

[ComputelessComputer]

• Introduces a new ModelDownloadNotification component that checks for the availability of local STT and LLM models and prompts the user to download them if they are not available
• Displays a toast notification when the models are not downloaded, with a button to initiate the download process
• Handles the download process for both STT and LLM models separately
• Refetches the model download status at regular intervals to ensure the notification is up-to-date
• Adds a new setting for the display language and a toast to show the selected language, allowing users to easily see and change the display language of the application
• Displays a toast notification when the user changes the display language, advising them to switch their speech recognition model to match the new language, with a button to open the AI settings page