Parse a user-agent string

Parses a user-agent string into a structured record: client (with its type, version, maker, rendering engine, and browser-family flags), the operator the traffic acts for, os, device, and classification flags like is_bot and is_ai_crawler. Supply the string via the ua query parameter, or omit it to parse the request's own User-Agent header ("what browser am I?"). Parsing is first-party: the strings you submit are never forwarded to a third-party service. A leaf the string doesn't reveal ships as null, and a block whose every leaf resolved null collapses to a single null (os, client.engine, operator, and any maker), so guard those before reading into them. See https://restcountries.com/docs/user-agent for the full reference.