Millijethwani18/fable-opus-desktop-kit — reverse-engineered prompt

Build me a polished browser based app called FableMind Studio that feels like a calm desktop workspace for thinking, writing, and coding with AI. I want it to run locally in the browser, save everything automatically on the device, and feel privacy first with no tracking or forced cloud account.

The main experience should be a chat style studio with branching conversation threads, so I can fork ideas, revisit older paths, and organize complex work instead of just scrolling one long chat. Add a task panel where I can break a big prompt into smaller threads, then compare and combine the results. It should support multiple languages, nice readable code blocks with copy and export, and a responsive layout that can switch between a focused single view and a richer multi pane view. Please include light, dark, sepia, and high contrast themes, plus simple custom style support.

If possible, add settings for connecting to Claude or OpenAI style APIs with my own key and endpoint, plus a fallback model option. Keep it simple, elegant, and ready to open from index.html. Look up current docs online if you need to.