fix(page-layout): respect tab layoutMode on standalone pages (#20856)

Standalone-page tabs with `layoutMode: CANVAS` were silently rendering
as GRID (border, padding, scroll). Now they render full-bleed, matching
the CANVAS contract elsewhere.

Three layered fixes:
- `getTabLayoutMode`: respect `tab.layoutMode` for `STANDALONE_PAGE`
(was hardcoded to GRID for any non-`RECORD_PAGE`)
- `getWidgetCardVariant`: CANVAS now wins regardless of page type —
refactored to early-return + exhaustive switch on `pageLayoutType`
- `FrontComponentWidgetRenderer`: removed hardcoded `overflow: auto`
(workflow/tasks/timeline widgets don't have it either)

New `getTabLayoutMode.test.ts`. Variant tests refactored to declarative
+ parameterized.

QA:

<img width="3024" height="1654" alt="CleanShot 2026-05-22 at 20 46
50@2x"
src="https://github.com/user-attachments/assets/cc61d459-6bc6-48de-ac79-d63a2ccd8957"
/>


https://github.com/user-attachments/assets/a3374e18-ad1b-4888-ab2b-d07730edccac

packages/twenty-front/src/modules/page-layout/utils/__tests__/getTabLayoutMode.test.ts

@@ -0,0 +1,46 @@
+import { type PageLayoutTab } from '@/page-layout/types/PageLayoutTab';
+import { getTabLayoutMode } from '@/page-layout/utils/getTabLayoutMode';
+import {
+  PageLayoutTabLayoutMode,
+  PageLayoutType,
+} from '~/generated-metadata/graphql';
+
+const buildTab = (layoutMode: PageLayoutTabLayoutMode) =>
+  ({ layoutMode }) as unknown as PageLayoutTab;
+
+describe('getTabLayoutMode', () => {
+  describe('page types that respect tab.layoutMode', () => {
+    it.each([PageLayoutType.RECORD_PAGE, PageLayoutType.STANDALONE_PAGE])(
+      "returns the tab's layoutMode for %s",
+      (pageLayoutType) => {
+        const tab = buildTab(PageLayoutTabLayoutMode.CANVAS);
+
+        expect(getTabLayoutMode({ tab, pageLayoutType })).toBe(
+          PageLayoutTabLayoutMode.CANVAS,
+        );
+      },
+    );
+
+    it.each([PageLayoutType.RECORD_PAGE, PageLayoutType.STANDALONE_PAGE])(
+      'throws when tab is undefined for %s',
+      (pageLayoutType) => {
+        expect(() =>
+          getTabLayoutMode({ tab: undefined, pageLayoutType }),
+        ).toThrow('Tab layout mode is not defined');
+      },
+    );
+  });
+
+  describe('page types that ignore tab.layoutMode and default to GRID', () => {
+    it.each([PageLayoutType.DASHBOARD, PageLayoutType.RECORD_INDEX])(
+      'returns GRID for %s regardless of tab.layoutMode',
+      (pageLayoutType) => {
+        const tab = buildTab(PageLayoutTabLayoutMode.CANVAS);
+
+        expect(getTabLayoutMode({ tab, pageLayoutType })).toBe(
+          PageLayoutTabLayoutMode.GRID,
+        );
+      },
+    );
+  });
+});

packages/twenty-front/src/modules/page-layout/utils/getTabLayoutMode.ts

@@ -14,7 +14,10 @@ export const getTabLayoutMode = ({
   tab,
   pageLayoutType,
 }: GetTabLayoutModeParams): PageLayoutTabLayoutMode => {
-  if (pageLayoutType === PageLayoutType.RECORD_PAGE) {
+  if (
+    pageLayoutType === PageLayoutType.RECORD_PAGE ||
+    pageLayoutType === PageLayoutType.STANDALONE_PAGE
+  ) {
     assertPageLayoutTabHasDefinedLayoutModeOrThrow(tab);
 
     return tab.layoutMode;