Non-interactive empty-state hero container for mounted admin pages.

Displays a centered icon, title, and body copy. An optional actions slot renders a CTA (e.g. a <.button> component) inside the hero — the wrapper itself carries NO interactive affordances (tabindex, role="button", phx-click, :hover cursor change).

CMP-03 contract: this element must have cursor: default (not pointer) and no role implying interactivity. Only the element inside actions slot is interactive.