The logo/title/theme/favicon are static 'ScreenTinker' in index.html, and
applyBranding() only overrode them AFTER an async /api/white-label fetch - that
network delay was the flash, on every load and on switch (which reloads).
Now applyBranding caches the resolved white-label per workspace (keyed by the
JWT's current_workspace_id), and a tiny same-origin brand-prime.js loads
render-blocking right after the logo - so it applies the cached colors/name/
title/favicon/custom-css BEFORE first paint. CSP-safe (external 'self' script,
not inline). applyBranding still runs to refresh + re-cache. First-ever visit to
an uncached branded workspace still shows the default once; every load after is
flash-free.
