Track the browser of request

Return the browser where the request came from
Pattern matching user-agent is the way I can think of

Start by locating the request-tracking entry point and any existing tests in express-analytics, then trace how the user-agent value is received. Add browser information to the request result and verify it with a focused test; the issue names no file, test, or precise browser-output format, so those details must be established from the repository.

Written by the indexing model from the issue text.