Niek/chatgpt-web ? reverse-engineered prompt

Build me a simple one page ChatGPT style web app that works with OpenAI compatible chat APIs.

I want users to be able to pick a provider, paste in an API key, and then the app should find the available models and let them start chatting right away. Keep chats saved in the browser so they stay private, and make the UI fast, clean, and easy to use on mobile too. It should stream answers as they come in, support code blocks with easy copy buttons, and let people export a conversation as a Markdown file.

Please also include voice input and spoken replies, a few helpful starter prompts, and basic settings like prompt text and temperature. If it makes sense, add support for image generation through providers that can do it. Make it work as both a web app and a desktop app if possible, and feel free to look up current docs online if you need to.