Resolve the host's current palette to concrete colors and post it to the iframe. Call from the theme store's applyAndSet AND on 'texbrain:ready', so the editor is themed before first paint.
the iframe's contentWindow (null is a no-op — frame not mounted)
the embedded editor's origin (EDITOR_ORIGIN); never '*'
the active preset/mode/overrides/overrideAlphas
Resolve the host's current palette to concrete colors and post it to the iframe. Call from the theme store's applyAndSet AND on 'texbrain:ready', so the editor is themed before first paint.