- Button: `loading` always disables (|| not ??) — stops a double-submit
when a call-site passes an explicit boolean `disabled` (VideoEditor).
- playlists: track un-ingestable-but-live YouTube ids in the sync baseline
so a linked playlist containing a private/deleted video converges instead
of re-classifying it as a pending pull forever; re-attempt ingestion each
sync so a restored (private->public) video heals, and prune ids that
leave YouTube.
- SettingsPanel: download-auth section renders an honest error/loading
state (StateMessage + retry) instead of a bare empty section on a failed
credentials fetch; HU+EN loadError string.
- tests: reorder-order, partial-failure baseline hold, un-ingestable
converge/heal/prune, Button loading-disables, download-auth error/retry.
Introduce frontend/src/components/ui/Button.tsx — the one action-button primitive
(variants primary|danger|outline|ghost|glass|danger-outline; sizes xs|sm|md|lg|icon;
icon/iconOnly/label/loading/fullWidth/forwardRef). No focus-visible (already centralized
in index.css @layer base). Migrate the cleanest proof sites off btnCls, and flip the
channel Subscribe button to the outline variant so it matches Full history (the user's ask).
peter