feat(ui): fold the Workflows page into Dashboard → Analytics → Workflow

The workflow analytics now render under the Analytics tab's Workflow
sub-tab; ?tab= and ?sub= deep-link the Dashboard, /workflows redirects there,
and the sidebar drops its Workflows item.

client/src/App.tsx

@@ -41,7 +41,6 @@
  * - `./pages/Dashboard`
  * - `./pages/History`
  * - `./pages/SessionDetail`
- * - `./pages/Workflows`
  * - `./pages/SettingsHub`
  * - `./pages/Workspace`
  *
@@ -64,7 +63,6 @@ import { GlobalTooltip } from "./components/Tooltip";
 import { Dashboard } from "./pages/Dashboard";
 import { History } from "./pages/History";
 import { SessionDetail } from "./pages/SessionDetail";
-import { Workflows } from "./pages/Workflows";
 import { SettingsHub } from "./pages/SettingsHub";
 import { Workspace } from "./pages/Workspace";
 import { NotFound } from "./pages/NotFound";
@@ -99,7 +97,10 @@ export default function App() {
             <Route path="sessions" element={<History />} />
             <Route path="sessions/:id" element={<SessionDetail />} />
             <Route path="activity" element={<Navigate to="/sessions?view=events" replace />} />
-            <Route path="workflows" element={<Workflows />} />
+            <Route
+              path="workflows"
+              element={<Navigate to="/?tab=analytics&sub=workflow" replace />}
+            />
             <Route path="lanes" element={<Navigate to="/workspace" replace />} />
             <Route
               path="cc-config"