fix(commands): ADDSELECTED keeps CLAYER, adopts dimension style (#239)

Two follow-ups to ADDSELECTED:

- It no longer permanently changes the current layer/colour/linetype/
  lineweight. The template's properties are captured as the drawing
  defaults only while the launched draw command runs; a snapshot taken in
  cmd_add_selected is restored the moment that command ends (central hook
  in apply_cmd_result) or is interrupted by another command.
- Dimensions are supported: add_selected_verb maps each DimensionType to
  its DIM* command, and the template's dimension style is adopted as the
  current DIMSTYLE (restored afterwards). commit_entity_handle now stamps
  every new dimension with the current DIMSTYLE — the DIM commands left the
  default "Standard" on the entity, so a normal dimension also picks up
  the active style now.

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

src/app/properties.rs

@@ -667,6 +667,22 @@ impl OpenCADStudio {
             entity.as_entity_mut().set_layer(layer.clone());
         }
 
+        // A new dimension adopts the current dimension style (DIMSTYLE), like
+        // AutoCAD — the DIM commands leave the default "Standard" on the entity,
+        // so stamp the header's current style here. ADDSELECTED sets DIMSTYLE to
+        // the template's first, so a cloned dimension keeps its style (#239).
+        if let acadrust::EntityType::Dimension(ref mut d) = entity {
+            let cur = self.tabs[i]
+                .scene
+                .document
+                .header
+                .current_dimstyle_name
+                .clone();
+            if !cur.trim().is_empty() {
+                d.base_mut().style_name = cur;
+            }
+        }
+
         // INSUNITS: when inserting a block whose BlockRecord.units differ
         // from the host's header.insertion_units, scale the new INSERT so
         // 1 source-unit equals the matching host length. When either side