fix(dashboard): keep the on-screen keyboard down when the share sheet opens

Autofocusing the recipient input popped the keyboard over the bottom
sheet the moment it opened, hiding the access list before the user had
chosen what to do — the same reason the revoke flow already focuses
the dialog instead of the input. On touch-primary devices give the
dialog container initial focus (which also anchors the Tab trap);
desktop keeps the input autofocus.

src/gui/src/UI/Dashboard/UIShareModal.js

@@ -22,6 +22,7 @@ import item_icon from '../../helpers/item_icon.js';
 import { owner_of_path } from '../../helpers/path_owner.js';
 import { invalidate_shared_roots } from '../../helpers/shared_access.js';
 import { icons } from '../../helpers/actionIcons.js';
+import { isTouchPrimaryDevice } from './ContextMenu/ContextMenu.js';
 
 const { html_encode } = window;
 
@@ -137,9 +138,16 @@ export default function UIShareModal ({ path: item_path, name, owner, fsentry, $
     const $submit = $overlay.find('.share-modal-submit');
 
     // Focus returns to wherever the user was (usually the shared row) when
-    // the modal closes; the input takes it while the modal is up.
+    // the modal closes. While it's up, the recipient input takes it on
+    // desktop; on touch-primary devices the dialog itself does, because
+    // focusing the input would pop the on-screen keyboard over the sheet
+    // before the user has chosen what to do (add, change, or revoke).
     const el_previous_focus = document.activeElement;
-    $recipient.get(0)?.focus({ preventScroll: true });
+    if ( isTouchPrimaryDevice() ) {
+        $overlay.find('.share-modal').get(0)?.focus({ preventScroll: true });
+    } else {
+        $recipient.get(0)?.focus({ preventScroll: true });
+    }
 
     let closed = false;
     const close = () => {