feat: view tab widget toggle commands and unified SVG icon color scheme

Integrate NAVVCUBE, NAVBAR, PROPERTIES, FILETAB, LAYOUTTAB, TOOLPALETTES
and SHEETSET commands to toggle UI widgets at runtime. Add 15 new SVG icons
for view module tools previously using glyph fallbacks. Restyle all SVG
icons to use the established two-color scheme: #e0e0e0 for passive geometry,
#4cc9f0 for active/accent elements.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/ui/statusbar.rs

@@ -40,6 +40,8 @@ impl StatusBar {
         viewport_count: usize,
         // True when the user is editing inside a paper-space viewport (MSPACE).
         in_mspace: bool,
+        // Whether the layout tabs (Model/Paper) are visible (LAYOUTTAB).
+        show_layout_tabs: bool,
     ) -> Element<'a, Message> {
         let menu_btn = button(text("≡").size(14).color(ICON_COLOR))
             .on_press(Message::Command("MENU".into()))
@@ -107,14 +109,16 @@ impl StatusBar {
 
         let mut bar = Row::new().align_y(iced::Center).spacing(0);
         bar = bar.push(menu_btn);
-        for name in layouts {
-            let is_active = name == current_layout;
-            let renaming = rename_state
-                .filter(|(orig, _)| *orig == name)
-                .map(|(_, edit)| edit.as_str());
-            bar = bar.push(space_tab(name, is_active, renaming));
+        if show_layout_tabs {
+            for name in layouts {
+                let is_active = name == current_layout;
+                let renaming = rename_state
+                    .filter(|(orig, _)| *orig == name)
+                    .map(|(_, edit)| edit.as_str());
+                bar = bar.push(space_tab(name, is_active, renaming));
+            }
+            bar = bar.push(add_btn);
         }
-        bar = bar.push(add_btn);
         bar = bar.push(iced::widget::Space::new().width(Length::Fill));
         bar = bar.push(right_status);