feat(properties): conform entity property groups to PROPERTIES.md

Rewrite each entity's property builder to the per-entity group/row spec:
the correct sections (Geometry, Misc, Text, Pattern, Lines & Arrows, Leaders,
Block, …) with the spec's rows and real computed values — Diameter,
Circumference, Area, Delta X/Y/Z, Angle, Total angle, Arc length, Radius ratio,
etc. — plus apply routing for the editable rows.

Covers ~26 entities (Line, Circle, Arc, Point, Ellipse, Spline, polylines,
Ray/XLine, Insert, Text, MText, Hatch, Leader, MultiLeader, Tolerance, Solid,
Solid3D/Region/Body, meshes, MLine, Raster/Wipeout, Underlay, Table, Viewport,
Attribute, OLE). The 3D Visualization/Material group and the full Dimension
spec are deferred (they need document access for material/dimstyle name
resolution). Rows whose data is not in the pinned acadrust revision are shown
as empty placeholders, to be filled when the dependency is bumped.

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

src/entities/line.rs

@@ -73,6 +73,10 @@ fn grips(line: &Line) -> Vec<GripDef> {
 }
 
 fn properties(line: &Line) -> Vec<PropSection> {
+    let dx = line.end.x - line.start.x;
+    let dy = line.end.y - line.start.y;
+    let dz = line.end.z - line.start.z;
+    let angle = dy.atan2(dx).to_degrees().rem_euclid(360.0);
     vec![PropSection {
         title: "Geometry".into(),
         props: vec![
@@ -82,7 +86,11 @@ fn properties(line: &Line) -> Vec<PropSection> {
             edit("End X", "end_x", line.end.x),
             edit("End Y", "end_y", line.end.y),
             edit("End Z", "end_z", line.end.z),
+            ro("Delta X", "delta_x", format!("{dx:.4}")),
+            ro("Delta Y", "delta_y", format!("{dy:.4}")),
+            ro("Delta Z", "delta_z", format!("{dz:.4}")),
             ro("Length", "length", format!("{:.4}", line.length())),
+            ro("Angle", "angle", format!("{angle:.2}")),
         ],
     }]
 }