fix: show toggle unknown button while unknown column is shown

src/kanban/filterDefaultHiddenStatuses.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+import { TaskStatus } from "@/model/taskStatus";
+import { filterDefaultHiddenStatuses } from "./filterDefaultHiddenStatuses";
+
+describe("filterDefaultHiddenStatuses", () => {
+	it("excludes unknown when no unknown tasks and column not shown", () => {
+		const result = filterDefaultHiddenStatuses(false, []);
+		expect(result).not.toContain(TaskStatus.UNKNOWN);
+	});
+
+	it("includes unknown when unknown tasks exist", () => {
+		const result = filterDefaultHiddenStatuses(true, []);
+		expect(result).toContain(TaskStatus.UNKNOWN);
+	});
+
+	it("includes unknown when column is shown even without unknown tasks", () => {
+		const result = filterDefaultHiddenStatuses(false, [TaskStatus.UNKNOWN]);
+		expect(result).toContain(TaskStatus.UNKNOWN);
+	});
+});