feat(block-editor): edit definition properties in the Properties panel

Add the no-selection Block section with annotation, orientation, scaling, exploding, units, description and hyperlink controls. Integrate definition edits with editor history, save checkpoints and discard, and keep staged text tied to its definition.

Persist annotation and hyperlink metadata on the block record, migrate legacy marker values on edit, and honor orientation and hyperlink descriptions during block creation. Cover native DWG/DXF roundtrips and replacement after reopening.

src/app/properties.rs

@@ -1780,6 +1780,7 @@ impl OpenCADStudio {
         // Which entities the previous panel was built for — an uncommitted
         // edit buffer only survives a rebuild for the *same* selection.
         let prev_handles = std::mem::take(&mut self.tabs[i].properties.source_handles);
+        let previous_definition = self.tabs[i].properties.block_definition;
         let selected_group = self.tabs[i].properties.selected_group.clone();
 
         // Seed the per-thread unit context from the document header so the
@@ -2026,7 +2027,7 @@ impl OpenCADStudio {
                             value => value.to_string(),
                         })
                         .collect();
-                    let sections = vec![
+                    let mut sections = vec![
                         PropSection {
                             title: t!("General").into_owned(),
                             props: vec![
@@ -2261,8 +2262,14 @@ impl OpenCADStudio {
                             },
                         },
                     ];
+                    if let Some(section) = self.block_property_section(i) {
+                        sections.insert(5, section);
+                    }
                     ui::PropertiesPanel {
                         title: t!("No selection").into_owned(),
+                        block_definition: tab
+                            .active_block_edit_session()
+                            .map(|session| session.br_handle),
                         choice_combos: sections
                             .iter()
                             .flat_map(|section| section.props.iter())
@@ -2469,7 +2476,9 @@ filter={:.1} local={:.1} aggregate={:.1} entities={}",
             // Carry the in-progress edits only when the selection is unchanged
             // (a commit-triggered rebuild); a genuine selection change starts
             // with a clean buffer so no stale value leaks onto the new entity.
-            panel.edit_buf = if prev_handles == new_handles {
+            let same_target =
+                prev_handles == new_handles && previous_definition == panel.block_definition;
+            panel.edit_buf = if same_target {
                 edit_buf
             } else {
                 Default::default()
@@ -2477,11 +2486,7 @@ filter={:.1} local={:.1} aggregate={:.1} entities={}",
             // The active-row highlight only survives a rebuild for the same
             // selection (like the edit buffer); a selection change clears it so
             // an old row isn't marked active against new content.
-            panel.active_field = if prev_handles == new_handles {
-                active_field
-            } else {
-                None
-            };
+            panel.active_field = if same_target { active_field } else { None };
             panel.expanded_groups = expanded_groups;
             panel.collapsed_sections = collapsed_sections;
             panel.source_handles = new_handles;