fix: complete TechLog migration evidence

tests/features/tech-log/public-discovery-screens.test.tsx

@@ -372,18 +372,20 @@ describe("TechLog explore discovery", () => {
     ).toHaveAttribute("href", "/explore");
   });
 
-  it("renders an unknown kind as the source production plain 404", async () => {
+  it("keeps the unreachable unknown-kind client fallback accessible", async () => {
     const { router, container } = renderDiscoveryRoute(
       "TECH_LOG_EXPLORE_KIND",
       "/explore/unknown",
     );
 
     expect(router.state.location.pathname).toBe("/explore/unknown");
-    expect(await screen.findByText("Not Found", { exact: true })).toBeVisible();
+    expect(
+      await screen.findByRole("heading", { name: "페이지를 찾을 수 없습니다." }),
+    ).toBeVisible();
     expect(
       screen.queryByRole("heading", { name: "화면을 표시하지 못했습니다." }),
     ).not.toBeInTheDocument();
-    expect(container.querySelector(".site-frame")).toBeNull();
+    expect(container.querySelector(".site-frame")).not.toBeNull();
   });
 
   it("recovers a rejecting registered not-found runtime under its own chunk contract", async () => {