Implements Task 13: BrowsePane (marketplace list, kind/search filters, item
detail), InstallControls (global/per-project install, opt-out, hook confirm
gate), HookConfirmModal, AddMarketplaceModal, and ItemDetail. Also applies
pre-flight ruling F6: a per-marketplace Remove button with a confirm dialog
(mp.remove) warning that surviving installs become "Source removed" and can
be dropped via Forget on the Installed tab, plus an inline account
reassignment select (updateMarketplace + reloadState).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
