The home page's bottom-left settings button is FileSidebar's bottom
bar, which hardcoded an initials circle - the avatar work in
useConfigButtonIcon only affects the QuickAccessBar rail, which the
home page doesn't render. Add a layered useProfilePictureUrl hook
(core stub returns null; saas returns the auth context URL) and render
the picture inside the existing avatar circle, falling back to the
initial when absent or on image load failure.