feat(offset): open on the live preview for pre-selected objects; signed typed distance

With objects already selected, OFFSET opens at the side step with the
preview following the cursor instead of asking for a distance first
(#422). At the side step a typed distance places the offset at once on
the cursor's side, and a negative one on the other side; Enter at the
start repeats the last distance (#418). Erase and Layer, which lived on
the skipped distance step, are offered there too. With nothing selected
the distance-first flow is unchanged.

The opposite side is found by mirroring the cursor through its nearest
point on the outline, capped at half the offset distance so it cannot
cross a narrow gap back to the cursor's own side. Two new prompts are
added to the catalog and every locale.

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

locales/pl-PL/opencadstudio.ftl

@@ -3022,6 +3022,8 @@ modify =
     .offset-n-click-through-point-or-multiple = OFFSET__ocs_arg_n__ Punkt przelotowy lub [Multiple]:
     .offset-n-multiple-click-next-side-distance-d = OFFSET__ocs_arg_n__ Wielokrotne kliknięcie następnej strony [odległość __ocs_arg_d__]:
     .offset-n-multiple-click-next-through-point = OFFSET__ocs_arg_n__ Wielokrotne kliknięcie następnego punktu przelotowego:
+    .offset-n-click-through-point-or-type-distance = OFFSET__ocs_arg_n__  Kliknij punkt przelotowy lub wpisz odległość, ujemną dla drugiej strony [Multiple/Erase/Layer] <__ocs_arg_d__>:
+    .offset-n-multiple-click-through-point-or-type-distance = OFFSET__ocs_arg_n__ Wielokrotnie  Kliknij punkt przelotowy lub wpisz odległość, ujemną dla drugiej strony [Erase/Layer] <__ocs_arg_d__>:
     .offset-dimexo = Przesunięcie (DIMEXO)
     .overall-scale-dimscale = Skala ogólna (DIMSCALE)
     .pedit-enter-option = Opcja PEDIT Enter: