plugins::commands: the palette commands a site tab reports (validated and
capped as a whole) and the page script that runs one, now built from the
SiteSpec (runtime global, primary origin) instead of a hard-coded x.com.
devmode: the debounced polling watcher (plugins, custom.css, one theme
file), reload order, DevError and theme-file reading; the app turns the
document into its own theme state through a callback.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
