fpm::StaticFile
fpm::StaticFile struct keeps track of “static files”.
pub struct StaticFile {
    pub id: String,
    pub base_path: camino::Utf8PathBuf,
}
What is a “static file”?

Static file is a file that is not ftd file nor code file. Code file is any file for which we have syntax highlighting support by.

We detect this by finding the extension of the file and checking in ftd::render::KNOWN_EXTENSIONS.contains(ext).