VarunSinghBot/secondbrain ? reverse-engineered prompt

Build me a second brain app for taking and organizing notes, where I can sign in with Google or email and password, create rich text notes, and easily browse them from a dashboard. I want to be able to open a note, edit it with simple formatting like bold, italic, headings, and lists, then search across note titles, body text, and tags. It should let me filter notes by type like article, image, audio, or video, and generate shareable public links for individual notes.

Please make the app feel polished, with a few visual themes like light, dark, sepia, and ocean, plus different layout density options in settings. Include smooth transitions, a clear sidebar and top bar, and tag management so notes are easy to organize. Use the existing monorepo setup, keep the backend and frontend together in the main web app, and if you need to look up current docs online, go ahead.