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 <[email protected]>

locales/ru-RU/opencadstudio.ftl

@@ -3026,6 +3026,8 @@ modify =
     .offset-n-click-through-point-or-multiple = OFFSET__ocs_arg_n__ Нажмите на точку или [Множественное число]:
     .offset-n-multiple-click-next-side-distance-d = OFFSET__ocs_arg_n__ Несколько кликов на следующую сторону [расстояние __ocs_arg_d__]:
     .offset-n-multiple-click-next-through-point = OFFSET__ocs_arg_n__ Несколько кликов по следующей точке:
+    .offset-n-click-through-point-or-type-distance = OFFSET__ocs_arg_n__  Укажите точку прохождения или введите расстояние, отрицательное для другой стороны [Multiple/Erase/Layer] <__ocs_arg_d__>:
+    .offset-n-multiple-click-through-point-or-type-distance = OFFSET__ocs_arg_n__ Несколько  Укажите точку прохождения или введите расстояние, отрицательное для другой стороны [Erase/Layer] <__ocs_arg_d__>:
     .offset-dimexo = Отступ от объекта (DIMEXO)
     .overall-scale-dimscale = Общий масштаб (DIMSCALE)
     .pedit-enter-option = PEDIT Введите опцию: