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/mtext.rs

@@ -272,7 +272,14 @@ fn properties(t: &MText, text_style_names: &[String]) -> Vec<PropSection> {
                     "line_space_distance",
                     format!("{line_space_distance:.4}"),
                 ),
-                ro("Line space style", "line_space_style", String::new()),
+                ro(
+                    "Line space style",
+                    "line_space_style",
+                    match t.line_spacing_style {
+                        acadrust::entities::LineSpacingStyle::Exactly => "Exactly",
+                        _ => "At least",
+                    },
+                ),
                 ro(
                     "Background mask",
                     "background_mask",