Backend settings modal to setup application id, search api key, admin api key and Algolia index;
Backend permissions setting;
Frontend search box is replaced with Algolia search source. Visually there is no difference
Frontend post indexing/unindexing. Each post has to be indexed manually to avoid bunch of useless posts in the index (e.g. "Thank you ...", "It works/does not work ..." etc). This way you control what exactly should be indexed to keep your search results ever-green.

Installation

Current just checkout the source and follow the Flarum Documentation. When I'll find that more people are interested in this functionality I'll make easier to install.