fix: anchor dashboard rail labels

apps/nextjs/src/app/[locale]/boards/(content)/_client.module.css

@@ -36,6 +36,7 @@
 .gutter[data-board-editing="true"]::before {
   position: sticky;
   top: 0;
+  inset-inline-start: 0;
   z-index: 2;
   display: block;
   width: fit-content;

e2e/board-grid.spec.ts

@@ -990,6 +990,15 @@ describe("Board grid", () => {
       const emptyRightGutter = page.getByRole("complementary", { name: "Right dashboard rail" });
       await expect(emptyRightGutter).toHaveCount(1);
       expect((await expectBoundingBoxAsync(emptyRightGutter)).width).toBeGreaterThan(0);
+      await page.getByTestId("board-edit-mode-toggle").click();
+      await expect(emptyRightGutter).toHaveAttribute("data-board-editing", "true");
+      expect(
+        await emptyRightGutter.evaluate((element) => ({
+          content: getComputedStyle(element, "::before").content.replaceAll('"', ""),
+          insetInlineStart: getComputedStyle(element, "::before").insetInlineStart,
+          top: getComputedStyle(element, "::before").top,
+        })),
+      ).toEqual({ content: "Right dashboard rail", insetInlineStart: "0px", top: "0px" });
       expect(pageErrors).toEqual([]);
     } finally {
       runtimeResources?.stop();