feat(blocks): wire Stretch actions and independent reference evaluation

Author a native Stretch action from a Linear, Polar or XY parameter, a two-corner stretch frame, an object selection and a marker. Preview and retain its frame in BEDIT, with selectable and movable action markers.

Freeze line and planar lightweight-polyline vertex bindings, preserve curved-segment height, move wholly selected objects, and evaluate independent saved INSERTs from their definition. Retain native DWG/DXF data, copied-reference isolation and undo/redo.

Validate with synthetic frame, topology, parameter, history, Test Block, drawing-reference, COPY and roundtrip regressions: 340 block tests pass (6 existing opt-in ignored), plus 41 dock and 27 viewport tests. Other entity types, Polar Stretch, custom multipliers and chaining remain unsupported.

src/ui/window/authoring_palettes.rs

@@ -198,6 +198,7 @@ fn catalog(
     scale_error: Option<&'static str>,
     rotate_error: Option<&'static str>,
     flip_action_error: Option<&'static str>,
+    stretch_action_error: Option<&'static str>,
 ) -> Element<'static, Message> {
     let (entries, unavailable) = match tab {
         Tab::Parameters => (
@@ -219,8 +220,8 @@ fn catalog(
         let orientation_error = if *label=="Flip" {flip_error} else {point_error};
         let single=tab==Tab::Parameters&&matches!(*label,"Lookup"|"Basepoint");
         let lookup_action=tab==Tab::Actions&&*label=="Lookup";
-        let geometry_action=tab==Tab::Actions&&matches!(*label,"Move"|"Scale"|"Rotate"|"Flip");
-        let action_error=match *label {"Scale"=>scale_error,"Rotate"=>rotate_error,"Flip"=>flip_action_error,_=>move_error};
+        let geometry_action=tab==Tab::Actions&&matches!(*label,"Move"|"Scale"|"Stretch"|"Rotate"|"Flip");
+        let action_error=match *label {"Scale"=>scale_error,"Stretch"=>stretch_action_error,"Rotate"=>rotate_error,"Flip"=>flip_action_error,_=>move_error};
         let enabled = (geometry_action&&action_error.is_none())||(single&&point_error.is_none())||(lookup_action&&lookup_error.is_none())||(orientation && orientation_error.is_none()) || (visibility && visibility_error.is_none()) || ((point || distance) && point_error.is_none());
         let base = if enabled {
             icons::semantic(icon, 28.0)
@@ -266,7 +267,7 @@ fn catalog(
         } else if single {
             crate::t!(point_error.unwrap_or(if *label=="Basepoint" {"Place or relocate the dynamic block insertion anchor."}else{"Place a Lookup parameter, then use the Lookup action to edit its property table."})).into_owned()
         } else if geometry_action {
-            crate::t!(action_error.unwrap_or("Select a parameter endpoint, select the objects it controls, then place the action marker. Use the reference parameter grip in the drawing or Test Block.")).into_owned()
+            crate::t!(action_error.unwrap_or(if *label=="Stretch" {"Select a parameter endpoint, define the stretch frame, select its objects, then place the action marker."}else{"Select a parameter endpoint, select the objects it controls, then place the action marker. Use the reference parameter grip in the drawing or Test Block."})).into_owned()
         } else if lookup_action {
             crate::t!(lookup_error.unwrap_or("Create or edit property Lookup tables for this block.")).into_owned()
         } else {
@@ -284,7 +285,7 @@ fn catalog(
         } else if single {
             container(entry).id(if *label=="Lookup" {"authoring-tool-lookup"}else{"authoring-tool-basepoint"}).into()
         } else if geometry_action {
-            container(entry).id(match *label {"Move"=>"authoring-tool-move-action","Scale"=>"authoring-tool-scale-action","Rotate"=>"authoring-tool-rotate-action",_=>"authoring-tool-flip-action"}).into()
+            container(entry).id(match *label {"Move"=>"authoring-tool-move-action","Scale"=>"authoring-tool-scale-action","Rotate"=>"authoring-tool-rotate-action","Stretch"=>"authoring-tool-stretch-action",_=>"authoring-tool-flip-action"}).into()
         } else if lookup_action {
             container(entry).id("authoring-tool-lookup-table").into()
         } else {
@@ -405,6 +406,7 @@ pub fn view(
     scale_error: Option<&'static str>,
     rotate_error: Option<&'static str>,
     flip_action_error: Option<&'static str>,
+    stretch_action_error: Option<&'static str>,
 ) -> Element<'static, Message> {
     let tabs = column(Tab::ALL.into_iter().map(|category| {
         let label = category.label();
@@ -463,7 +465,8 @@ pub fn view(
                 move_error,
                 scale_error,
                 rotate_error,
-                flip_action_error
+                flip_action_error,
+                stretch_action_error
             ))
             .width(Fill)
             .height(Fill),