feat(xref): row-level context menu actions and unified split-button toolbar

Right-click actions bound to the row under the cursor, split-button toolbar groups with shared borders and hover states, and a notice when an operation needs a selection first.

locales/pl-PL/opencadstudio.ftl

@@ -3304,6 +3304,7 @@ insert =
     .revolve-select-objects-or-mode = REVOLVE  Wybierz obiekty do obrotu lub [Tryb] (Enter kończy):
 
     .path = Path:
+    .xref-file-references = File References
 model =
     .create = Utwórz
     .boolean = Operacje boolowskie