test: prove TechLog UI migration parity

tests/component/router.test.tsx

@@ -343,20 +343,12 @@ describe("generic application router", () => {
     expect(window.location.pathname).toBe("/projects");
   });
 
-  it("renders the Public shell and TechLog not-found route", async () => {
+  it("renders the source-compatible plain TechLog not-found response", async () => {
     window.history.pushState({}, "", "/missing");
     renderRouter();
 
-    expect(
-      await screen.findByRole("heading", {
-        name: "404",
-        level: 1,
-      }),
-    ).toBeVisible();
-    expect(
-      screen.getByRole("heading", { name: "This page could not be found." }),
-    ).toBeVisible();
-    expect(screen.getByRole("navigation", { name: "주요 탐색" })).toBeVisible();
+    expect(await screen.findByText("Not Found", { exact: true })).toBeVisible();
+    expect(screen.queryByRole("navigation", { name: "주요 탐색" })).not.toBeInTheDocument();
   });
 
   it("keeps Studio routes inside the persistent Studio layout", async () => {