rebase: port hyperhive#2874's composedPath() click-retarget fix into hive-dialog.js

#2875 (merged) fixed this on main's flat modal.js before #2793's
component-dir split landed. Porting the same one-line fix here now
instead of leaving it as a rebase landmine for whichever PR merges
second.

frontend/packages/shared/src/hive-dialog/hive-dialog.js

@@ -80,7 +80,19 @@ class HiveDialog extends HTMLElement {
     root.append(box);
 
     this.addEventListener('click', (e) => {
-      if (dismissable && e.target === this) done(null);
+      // `e.target` is retargeted to `this` (the host) for ANY click that
+      // originated inside the shadow tree, once it bubbles out to a
+      // listener attached on the host itself — per spec, retargeting
+      // applies to every ancestor outside the shadow tree, and the host
+      // element's own light-DOM-side listeners count as outside. So
+      // `e.target === this` was true for every click inside `.box` too
+      // (title, message, a bare checkbox row with no button to consume
+      // it first), not just genuine backdrop clicks — dismissing the
+      // whole dialog on, say, a checkbox click.
+      // `composedPath()[0]` is the true original target, unaffected by
+      // retargeting: it's `this` only when nothing inside the shadow
+      // tree was actually under the cursor, i.e. a real backdrop click.
+      if (dismissable && e.composedPath()[0] === this) done(null);
     });
     document.addEventListener('keydown', onKey, true);