chore: format the tree and clear ruff's findings

Applies ruff format, ruff check --fix and prettier, so CI can gate on all three.
The surviving unused imports were all re-exports in __init__.py, now covered by a
per-file ignore; the pdf.js viewer and the generated openapi types join the
vendored code that eslint and prettier already skip.

frontend/src/lib/components/view/book-grid.svelte

@@ -73,8 +73,8 @@
 										bookOps.deleteDialogTitle = `Delete "${book.title}"?`;
 										bookOps.deleteFn = async (deleteFiles: boolean) => {
 											await bookOps.deleteBooks([book.id], deleteFiles);
-											libraryState.activeLibrary!.total!--
-											bookshelfState.deletedBooks([book])
+											libraryState.activeLibrary!.total!--;
+											bookshelfState.deletedBooks([book]);
 										};
 										bookOps.deleteDialogOpen = true;
 									}}