fix(ui): restore brand across anonymous and error pages

Assisted-by: Codex:GPT-5

routers/common/errpage_test.go

@@ -27,12 +27,21 @@ func TestRenderPanicErrorPage(t *testing.T) {
 		assert.Contains(t, respContent, `class="page-content status-page-500"`)
 		assert.Contains(t, respContent, `</html>`)
 		assert.Contains(t, respContent, `lang="en-US"`) // make sure the locale work
+		assertNavbarBrand(t, respContent)
 
 		// the 500 page doesn't have normal pages footer, it makes it easier to distinguish a normal page and a failed page.
 		// especially when a sub-template causes page error, the HTTP response code is still 200,
 		// the different "footer" is the only way to know whether a page is fully rendered without error.
 		assert.False(t, test.IsNormalPageCompleted(respContent))
 	})
+	t.Run("ServiceUnavailableHTML", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		req := &http.Request{URL: &url.URL{}, Header: http.Header{"Accept": []string{"text/html"}}}
+		req = req.WithContext(reqctx.NewRequestContextForTest(t.Context()))
+		renderServiceUnavailable(w, req)
+		assert.Equal(t, http.StatusServiceUnavailable, w.Code)
+		assertNavbarBrand(t, w.Body.String())
+	})
 	t.Run("Plain", func(t *testing.T) {
 		w := httptest.NewRecorder()
 		req := &http.Request{URL: &url.URL{}}
@@ -42,6 +51,13 @@ func TestRenderPanicErrorPage(t *testing.T) {
 	})
 }
 
+func assertNavbarBrand(t *testing.T, content string) {
+	t.Helper()
+	assert.Contains(t, content, `class="navbar-brand-copy"`)
+	assert.Contains(t, content, "荣刻科技")
+	assert.Contains(t, content, "RONCARVE TECHNOLOGY")
+}
+
 func TestMain(m *testing.M) {
 	unittest.MainTest(m)
 }