Replaced `.to_str().unwrap()` with `.to_string_lossy()` when converting
`PathBuf` to `String` to prevent potential crashes if the path contains
invalid Unicode. This change improves the robustness of both the CLI
and GUI components when handling file paths.
- Modified `src/bin/cli.rs` to safely handle `file_path`.
- Modified `src/gui/mod.rs` to safely handle `path` in `play_file`.
Co-authored-by: arabianq <55220741+arabianq@users.noreply.github.com>
