Pure browser fingerprint data — the canonical source for browser identity.
Holds the StealthProfile selector, per-profile ProfileFacts (User-Agent,
navigation headers, hardware, client hints), and the canonical HeaderProfile
header catalog. This crate intentionally has no runtime, HTTP, TLS, browser, or
async dependencies. It sits below scanclient and stealth so both crates can
derive browser identity from one source without creating a dependency cycle.
Naming: StealthProfile is the canonical selector; ProfileFacts is its data;
a <Domain>Profile (e.g. HeaderProfile) is a pure derived projection for one
domain. One type per projection — HeaderProfile is the single browser-header
catalog type, re-exported unchanged by scanclient and stealth.