feat(layout): copy a layout from its tab menu (#1822)

The layout tab's right-click menu gains New Layout, Copy, Page Setup
and Plot beside Rename and Delete. Copy makes "<name> (2)" with the
source's page setup, sheet view and every paper-space object,
viewports included, and opens it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

locales/es-ES/opencadstudio.ftl

@@ -683,6 +683,7 @@ common =
     .layers = Capas
     .layout = Presentación
     .layout-name-silindi = Se eliminó la presentación «__ocs_fmt_0__»
+    .layout-copied = Layout "__ocs_fmt_0__" copied as "__ocs_fmt_1__"
     .layout-new-name-created-use-mview-to-add-a-vie = Se creó la presentación «__ocs_fmt_0__»; use MVIEW para añadir una ventana gráfica
     .layout-orig-new-name = Presentación «__ocs_fmt_0__» → «__ocs_fmt_1__»
     .layout-name-created = Se creó la presentación «__ocs_fmt_0__».