fix(ui): close menu dropdowns on outside click and Esc, add an X to Recent

[angela-helios]

The Recent-searches popup on Search / Saved Queries only closed by re-clicking its toggle (or by picking an entry). Manual testing flagged that it should also close on an outside click and from an explicit control.

What changed

• addbox.js (UI: Add-tenant panel can't be cancelled — no close (×) control, no Esc, no click-outside #545) now covers <details class="menu"> dropdowns as well as details.addbox: an outside click closes any open panel, Esc closes them, and [data-addbox-close] closes its own panel. That picks up the Recent popup and the sidebar's tenant and FHIR-version selectors, which had the same gap — all the chrome dropdowns now behave alike.
• The Recent panel's heading row gains an X (data-addbox-close, aria-label/title from the existing ui-close key, so no new i18n strings).
• The dropdowns remain fully usable without JavaScript — the script only adds ways out, same contract as UI: Add-tenant panel can't be cancelled — no close (×) control, no Esc, no click-outside #545.

Tests

• Extended the existing queries-page render test to assert the close control ships (data-addbox-close).
• cargo test -p helios-ui --lib: 67 passed.
• Exercised manually: outside click, Esc, and the X on the Recent popup; outside click and Esc on the tenant and version menus.