Support filtering filenames

My papers folder is quite large and it would be neat to support some sort of basic filtering on filename mechanism. I personally had in mind something like the VS Code command palette

Look at the TUI file browser code to understand how files are listed. Implement a filtering mechanism similar to VS Code's command palette, likely modifying the UI component that displays filenames. Test by running the tool on a sample PDF directory to ensure filtering works interactively.

索引モデルが issue の本文から書いたものです。