feat(properties): fill placeholder rows from acadrust fields + doc lookups

Bump acadrust to a46cb8b (spline knot parameterization + mtext line-space
style now stored) and populate rows the builders left blank:

Entity-local: spline Knot Parameterization + closed-spline Area (shoelace),
mtext Line space style, hatch Spacing (pattern-line offset), leader Text
offset (annotation offset), region Area + Perimeter (wire-loop approx).

Doc-dependent (resolved in app/properties.rs where the document is
reachable): insert Block Unit + Unit factor (block record units vs
INSUNITS), underlay Name + Path (definition object), leader Text style /
vertical placement / overall scale and tolerance Text style (dimension
style), multileader Max points + segment angles (mleader style).

Rows needing an annotation-scale / sheet-set subsystem or an internal
PDF/DWF layer parser are intentionally left blank.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/entities/leader.rs

@@ -231,7 +231,11 @@ fn properties(leader: &Leader) -> Vec<PropSection> {
 
     let text = vec![
         edit("Text height", "text_height", leader.text_height),
-        ro("Text offset", "text_offset", String::new()),
+        ro(
+            "Text offset",
+            "text_offset",
+            format!("{:.4}", leader.annotation_offset.length()),
+        ),
         ro("Text style", "text_style", String::new()),
         ro("Text color", "text_color", color_str(&leader.override_color)),
         ro("Text position vert", "text_pos_vert", String::new()),