v0.7.8

Added

• ua plugin (global) + head constants — low-entropy device & browser
  identity JS can read but CSS can't, written once as --const-ua-*:
  --const-ua-platform (macos / windows / linux / android / ios /
  chromeos / unknown), --const-ua-browser (chrome / edge / firefox /
  safari / opera / samsung / unknown), --const-ua-engine (blink /
  gecko / webkit / unknown), --const-ua-version (browser major, 0 if
  unknown), --const-ua-mobile (1 / 0). Branch on the client with no JS or
  media query — @container style(--const-ua-engine: webkit) { … }. Prefers
  structured UA Client Hints (navigator.userAgentData, Chromium) and falls back
  to a best-effort userAgent-string sniff on Firefox / Safari. Low-entropy
  only — no getHighEntropyValues, device model, full version, or architecture,
  so it adds no fingerprinting surface beyond what request headers already expose.
  The same five constants are also written synchronously by the head entry
  (import 'prop-for-that/head') for FOUC-safe, pre-paint branching. Typed mode
  registers the strings as <custom-ident> and the numbers as <integer>.