feat(attedit): enhanced attribute editor with 3 tabs

Grow the attribute editor into a three-tab enhanced editor:
- Attribute: the tag/prompt/value list; click a row to select it, edit
  its value below.
- Text Options: the selected attribute's Text Style, Justification,
  Height, Rotation, Width Factor, Oblique Angle, Backwards, Upside down.
- Properties: the selected attribute's Layer, Linetype, Color,
  Lineweight (the colour list also surfaces a non-standard current
  colour so it displays and round-trips).

Applying writes value, text-formatting and common-property edits back to
each attribute positionally (guarded on block name + count), with undo
and a repaint. OK/Cancel are replaced by a single Apply button in a top
toolbar that commits but keeps the dialog open, matching the other modal
windows — the frame ✕ closes and discards un-applied edits. The frame
adopts the shared style-window palette, tab styling and sizing.

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

src/app/view/mod.rs

@@ -1363,7 +1363,7 @@ impl OpenCADStudio {
             OverwriteWarning => (420, 180),
             SaveDialog => (560, 480),
             PointStyle => (360, 470),
-            AttributeEditor => (460, 440),
+            AttributeEditor => (640, 500),
         };
         Some((w as f32 + EXTRA_W, h as f32 + EXTRA_H))
     }

src/app/view/modal.rs

@@ -511,14 +511,36 @@ impl OpenCADStudio {
                 360,
                 470,
             ),
-            super::super::ModalKind::AttributeEditor => sized(
-                crate::ui::window::attribute_editor::view_window(
-                    &self.attr_editor_block,
-                    &self.attr_editor_fields,
-                ),
-                460,
-                440,
-            ),
+            super::super::ModalKind::AttributeEditor => {
+                let doc = &self.tabs[self.active_tab].scene.document;
+                let layers: Vec<String> = doc.layers.iter().map(|l| l.name.clone()).collect();
+                let mut linetypes: Vec<String> = vec!["ByLayer".to_string()];
+                linetypes.extend(
+                    doc.line_types
+                        .iter()
+                        .map(|lt| lt.name.clone())
+                        .filter(|n| !n.is_empty() && n != "ByLayer"),
+                );
+                let styles: Vec<String> = doc
+                    .text_styles
+                    .iter()
+                    .map(|s| s.name.trim().to_string())
+                    .filter(|n| !n.is_empty())
+                    .collect();
+                sized(
+                    crate::ui::window::attribute_editor::view_window(
+                        &self.attr_editor_block,
+                        &self.attr_editor_rows,
+                        self.attr_editor_selected,
+                        self.attr_editor_tab,
+                        layers,
+                        linetypes,
+                        styles,
+                    ),
+                    640,
+                    500,
+                )
+            }
             super::super::ModalKind::SaveDialog => sized(
                 save_as_dialog_window(
                     &self.save_dialog_filename,