Add a host-prefs option to configurePlannotatorUI so embedded hosts can preset one-time UI state

[ddiall]

One-time UI state (permission-mode choice, feature-announcement dismissals,
update banner) persists via per-origin localStorage. For embedded hosts
(iframe), storage can be partitioned or origins can change per session
(e.g. per-session ports), so these dialogs reappear on every session.

The published UI packages already expose a host-override seam
(configurePlannotatorUI). Proposal: extend it with an initial-prefs object
(e.g. { permissionMode, dismissedAnnouncements, skipTours }) that the editor
honors on boot, so a host can preset state instead of depending on
localStorage.

[ddiall]

From the same integration in #1344: we embed the annotate UI in an iframe inside the Hermes Agent desktop app. Per-origin localStorage is unreliable there — storage partitioning plus per-session ports means one-time dialogs (permission setup, feature announcements) come back every session. A host-prefs seam in configurePlannotatorUI would let us preset that state once at boot. Happy to contribute the implementation and document the seam with our integration as the reference consumer.