fix: guard recursive section rendering

apps/nextjs/src/components/board/sections/gridstack/gridstack.spec.ts

@@ -0,0 +1,11 @@
+import { describe, expect, test } from "vitest";
+
+import { filterRecursiveInnerSections } from "./gridstack";
+
+describe("filterRecursiveInnerSections", () => {
+  test("removes sections that would recursively render an ancestor", () => {
+    const innerSections = [{ id: "safe" }, { id: "parent" }, { id: "root" }];
+
+    expect(filterRecursiveInnerSections(innerSections, new Set(["root", "parent"]))).toEqual([{ id: "safe" }]);
+  });
+});