Annotate UI: allow embedded hosts to skip the permission-mode setup dialog

The annotate UI shows a one-time "Permission Mode Preservation" setup dialog
(Auto-accept Edits / Auto Mode / Bypass / Manual) for any unconfigured origin.

This dialog belongs to Claude Code plan-mode hook semantics. When the UI is
embedded in a host app (iframe) or driven by a non-hook client, it is pure
friction with no meaning — and because the choice persists per origin
(host:port), it reappears whenever the port changes or embedded storage is
partitioned.

Proposal: an env flag (e.g. PLANNOTATOR_SKIP_PERMISSION_SETUP=1) or query
param that suppresses the dialog; or skip it when the origin is not a hook
integration. Happy to implement — please confirm the trigger path
(PermissionModeSetup in the editor) and bless the flag name.