test(a11y): cover delayed and interrupted Map Source focus

Keep the Esri settlement assertion exact, verify selected-source focus and Tab departure in Chromium, cancel pending work during disposal, and document the focused behavior.

src/mapSourceFocus.test.mjs

@@ -230,3 +230,10 @@ test('pointer leave preserves established keyboard focus and the open tray', ()
 });
 
 
+
+test('disposed UI cannot complete a pending handoff', () => {
+  const h = harness({ hidden: true }); h.key(); h.tick();
+  h.manager._disposed = true; h.show(); h.drain();
+  assert.equal(h.document.activeElement, h.disclosure);
+  assert.equal(h.calls(), 1); assert.equal(h.timers.size, 0);
+});