feat(iced): make toolbox expandable/collapsible to 2 columns

hcie-iced-app/crates/hcie-iced-gui/src/app.rs

@@ -264,6 +264,8 @@ pub struct HcieIcedApp {
     pub bool_shape_a: Option<usize>,
     /// Boolean operation shape B selector index (geometry panel).
     pub bool_shape_b: Option<usize>,
+    /// Whether the toolbox is expanded to 2 columns (false = single column 36px, true = 2 columns 72px).
+    pub sidebar_expanded: bool,
 }
 
 /// A recently opened file entry.
@@ -779,6 +781,9 @@ pub enum Message {
     ViewerPrev,
     ViewerNext,
     ViewerEnter,
+
+    // ── Toolbox expand/collapse ─────────────────────────
+    SidebarToggleExpanded,
 }
 
 /// Convert a FilterType enum to the engine's string filter ID.
@@ -1113,6 +1118,7 @@ impl HcieIcedApp {
             vector_drag_last: None,
             bool_shape_a: None,
             bool_shape_b: None,
+            sidebar_expanded: false,
         };
 
         // Apply saved settings to tool state
@@ -5147,6 +5153,10 @@ impl HcieIcedApp {
                 }
             }
 
+            Message::SidebarToggleExpanded => {
+                self.sidebar_expanded = !self.sidebar_expanded;
+            }
+
             Message::NoOp => {}
 
             Message::TabletTouch { x, y, pressed } => {
@@ -5257,7 +5267,7 @@ impl HcieIcedApp {
             self.active_menu,
         );
 
-        // Toolbox — fixed 36px strip on the left edge (outside dock)
+        // Toolbox — 36px strip (single column) or 72px (2 columns) on the left edge
         let toolbox = crate::sidebar::view(
             &self.tool_state,
             &self.fg_color,
@@ -5266,6 +5276,7 @@ impl HcieIcedApp {
             self.active_tool_slot,
             self.sub_tools_open,
             &self.slot_last_used,
+            self.sidebar_expanded,
         );
 
         // Merged toolbar: icon buttons + tool options in one row