fix(sw): expand viewer model layout tabs and strengthen responsive tests

src/sw/sw-viewer.stories.tsx

@@ -148,9 +148,15 @@ export const States: Story = {
           { type: "menu", id: "menu-disabled", label: "Dropdown (disabled)", disabled: true, entries: [] },
         ],
       },
+      // 2026-10-23: the Model / Layout tabs get a field group of their own, as in the viewer demo, so the Story shows
+      // their width rule (equal buttons, the field face up to 378px with room).
+      {
+        id: "tabs", label: "탭", surface: "field", items: [
+          { type: "tabs", id: "tabs", label: "탭", value: "model", options: [{ value: "model", label: "Model", count: 17377 }, { value: "layout", label: "Layout", count: 237 }, { value: "off", label: "Disabled", disabled: true }] },
+        ],
+      },
       {
         id: "field", label: "field 면", surface: "field", items: [
-          { type: "tabs", id: "tabs", label: "탭", value: "model", options: [{ value: "model", label: "Model", count: 17377 }, { value: "layout", label: "Layout", count: 237 }, { value: "off", label: "Disabled", disabled: true }] },
           { type: "switch", id: "on", label: "Switch on", checked: true },
           { type: "switch", id: "off", label: "Switch off", checked: false },
           { type: "switch", id: "sw-disabled", label: "Disabled", checked: false, disabled: true },