feat(macos): add Allow Canvas toggle to settings

apps/macos/Sources/Clawdis/GeneralSettings.swift

@@ -51,6 +51,11 @@ struct GeneralSettings: View {
                         subtitle: "Enable idle blinks and wiggles on the status icon.",
                         binding: self.$state.iconAnimationsEnabled)
 
+                    SettingsToggleRow(
+                        title: "Allow Canvas",
+                        subtitle: "Allow the agent to show and control the Canvas panel.",
+                        binding: self.$state.canvasEnabled)
+
                     SettingsToggleRow(
                         title: "Enable debug tools",
                         subtitle: "Show the Debug tab with development utilities.",
@@ -73,6 +78,11 @@ struct GeneralSettings: View {
             self.refreshCLIStatus()
             self.refreshGatewayStatus()
         }
+        .onChange(of: self.state.canvasEnabled) { _, enabled in
+            if !enabled {
+                CanvasManager.shared.hideAll()
+            }
+        }
     }
 
     private var activeBinding: Binding<Bool> {