Do not make the ingest folder

A folder that Bindery made hid a missing volume mount. The books went
to a folder inside the container, and CWA never saw them. A missing
folder is now an error in the log at the start, and each upload fails
with a message that names the mount.

tests/test_calibre_db.py

@@ -250,6 +250,7 @@ def test_library_database_failure_keeps_the_http_lookup(library_db, monkeypatch,
 def test_database_book_id_reaches_the_epub_sidecar(client, library_db, monkeypatch, tmp_path, saved_id, saved_uuid):
     monkeypatch.setattr(config, "CALIBRE_DB_PATH", library_db)
     monkeypatch.setattr(config, "INGEST_DIR", tmp_path / "ingest")
+    config.INGEST_DIR.mkdir(exist_ok=True)
     remote = CwaClient("")
     remote.session.get = Mock(side_effect=AssertionError("No HTTP lookup needed"))
     monkeypatch.setattr(orchestrator, "cwa", lambda: remote)