feat(properties): audit editable vs read-only across all entities

Reclassify every property row to match standard palette behaviour: a row
is editable only when its value maps directly to a stored field AND its
apply_geom_prop handler is wired; computed/derived/count/handle/
cross-object values stay read-only.

Newly editable (all apply-wired): attribute tag/prompt; ellipse major
radius; hatch Double; lwpolyline closed/linetype-gen; mline style;
multileader annotative/landing/background-fill; polyline 2D+3D vertex
coords/segment widths/linetype-gen; shape style; spline control/fit
point coords, weight, fit tolerance, tangents; table break-option flags;
text alignment point, upside-down, backward; underlay display flags.

Corrections: spline Degree -> read-only (editing desynced the knot
vector); removed a duplicate leader "Arrowhead" row.

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

src/entities/attribute.rs

@@ -386,8 +386,16 @@ impl Grippable for AttributeDefinition {
 impl PropertyEditable for AttributeDefinition {
     fn geometry_properties(&self, text_style_names: &[String]) -> Vec<PropSection> {
         let mut text_props = vec![
-            ro("Tag", "att_tag", self.tag.clone()),
-            ro("Prompt", "att_prompt", self.prompt.clone()),
+            Property {
+                label: "Tag".into(),
+                field: "att_tag",
+                value: PropValue::EditText(self.tag.clone()),
+            },
+            Property {
+                label: "Prompt".into(),
+                field: "att_prompt",
+                value: PropValue::EditText(self.prompt.clone()),
+            },
             Property {
                 label: "Value".into(),
                 field: "att_default",
@@ -501,6 +509,14 @@ impl PropertyEditable for AttributeDefinition {
 
     fn apply_geom_prop(&mut self, field: &str, value: &str) {
         // String / enum fields first.
+        if field == "att_tag" {
+            self.tag = value.to_string();
+            return;
+        }
+        if field == "att_prompt" {
+            self.prompt = value.to_string();
+            return;
+        }
         if field == "att_default" {
             if !self.flags.constant {
                 self.default_value = value.to_string();
@@ -645,7 +661,11 @@ impl PropertyEditable for AttributeEntity {
             PropSection {
                 title: "Text".into(),
                 props: vec![
-                    ro("Tag", "atte_tag", self.tag.clone()),
+                    Property {
+                        label: "Tag".into(),
+                        field: "atte_tag",
+                        value: PropValue::EditText(self.tag.clone()),
+                    },
                     ro("Prompt", "atte_prompt", String::new()),
                     Property {
                         label: "Value".into(),
@@ -746,6 +766,10 @@ impl PropertyEditable for AttributeEntity {
     }
 
     fn apply_geom_prop(&mut self, field: &str, value: &str) {
+        if field == "atte_tag" {
+            self.tag = value.to_string();
+            return;
+        }
         if field == "atte_val" {
             if !self.flags.constant {
                 self.value = value.to_string();