fix(dimension): a dimension drawn live matches its baked block

Once edited, a dimension is drawn live instead of from its *D block;
on the #898 drawing that differed in three places:

- Oblique / architectural-tick strokes were DIMASZ/2 to each side, the
  block's are DIMASZ/sqrt(2) (its unit stroke runs corner to corner).
- Arrowheads and ticks shared the dimension line's wire, so a dashed
  dim line broke its ticks into stubs. They get their own solid wire
  (and explode as lines as before).
- A diameter's user-positioned text was lifted by the DIMTAD offset even
  when the stored point already was the text's middle, as a file saved
  elsewhere writes it; it is lifted only when it lies on the leader
  (#1323's case).

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

src/modules/draw/modify/explode.rs

@@ -466,6 +466,7 @@ fn dim_geom_entities(
     for (points, common) in [
         (geometry.ext_lines.as_slice(), ext_common),
         (geometry.dim_lines.as_slice(), dim_common),
+        (geometry.arrow_lines.as_slice(), dim_common),
     ] {
         for run in points.split(|point| point[0].is_nan()) {
             for pair in run.windows(2) {