annotation: TEXT/MTEXT store the model height of their default scale

Annotative text in DWG/DXF holds the model height of its default
(native) scale representation; other scales draw it at the ratio of the
two. OCS read the stored value as paper height and multiplied it by the
annotation scale again, so text from AutoCAD came out far too small
(#1734), and annotative text OCS wrote came out too small in AutoCAD.

- Rendering uses the active/native context ratio (1 when the object has
  no representation for the displayed scale).
- TEXT with an annotative style asks for the paper height, stores the
  model height of the creation scale and gets that context; MTEXT
  starts from the model height; ANNOUPDATE converts a fixed style
  height the same way.
- Properties: the Height row of annotative TEXT and MTEXT is the paper
  height at the displayed scale, with the model height beside it, and
  an edit converts back. MTEXT shows Annotative when it has contexts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/commands/display.rs

@@ -1608,12 +1608,14 @@ impl OpenCADStudio {
                 }
                 self.push_undo_snapshot(i, "ANNOUPDATE");
                 let scale = self.tabs[i].scene.creation_annotation_scale_handle();
+                let paper_to_model = self.tabs[i].scene.creation_annotation_multiplier();
                 let mut updated = 0usize;
                 for handle in &handles {
                     if crate::scene::annotative::update_entity_from_annotation_style(
                         &mut self.tabs[i].scene.document,
                         *handle,
                         scale,
+                        paper_to_model,
                     ) {
                         updated += 1;
                     }

src/app/commands/draw.rs

@@ -2697,6 +2697,16 @@ impl OpenCADStudio {
                     .header
                     .current_text_style_name
                     .clone();
+                // An annotative style's default height is on paper; the editor
+                // and the entity work in the model height of this scale.
+                let height = if crate::scene::annotative::text_style_is_annotative(
+                    &self.tabs[i].scene.document,
+                    &style,
+                ) {
+                    height * self.tabs[i].scene.creation_annotation_multiplier()
+                } else {
+                    height
+                };
                 let new_cmd = MTextCommand::with_defaults(height, style);
                 self.command_line.push_info(&new_cmd.prompt());
                 self.tabs[i].active_cmd = Some(Box::new(new_cmd));