feat: Save book file path, refactoring

Close #1

src/application/services/books.rs

@@ -68,13 +68,14 @@ impl Books {
     }
 
     pub fn add_books_from_path(&mut self) {
-        let iter = fs::Loader::new(PathBuf::from(&self.root));
+        let books = fs::Loader::new(PathBuf::from(&self.root))
+            .into_iter()
+            .map(|mut book| {book.source =  book.source.strip_prefix(&self.root).unwrap().into(); book})
+            .collect();
 
         match self.repo.lock() {
             Ok(mut repo) => {
-                for book in iter {
-                    repo.add(book);
-                }
+                repo.bulk_add(books);
             }
             Err(err) => eprintln!("{}", err),
         }