29nls/chessweb — reverse-engineered prompt

Build me a local web chess app where I can play on an interactive board against a strong engine and also use it for analysis. I want a clean modern interface with normal chess controls like make moves, undo, redo, reset, flip the board, and see an evaluation bar update while the engine thinks.

Please make it work with chess engines placed in a local chessengines folder, and let me switch between available engines. I also want simple engine settings I can change, like depth, move time, threads, and hash size. Add FEN and PGN import and export, plus an option for the engine to automatically play the other side. If Syzygy tablebases are present in the expected folder, use them for endgames.

Set up whatever frontend and backend pieces are needed so the board talks to a UCI engine smoothly and updates in real time. Make it easy to run locally with clear startup steps. If anything is unclear, look up current docs online and choose sensible defaults.