Calibre 9.7 adds offline mode for content server and annotation grouping

Calibre 9.7 introduces full offline mode for the content server when using HTTPS connections, enabling access without an internet connection. The release also debuts an improved annotations browser, allowing grouping of search results by any field. Additional updates include touchpad pinch-to-zoom support in the e-book viewer and multiple bug fixes, notably for annotation saving and content server search errors.