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/pages/__tests__/screens.snapshot.test.tsx

@@ -559,6 +559,17 @@ describe("screen snapshots", () => {
   it("Dashboard", async () => {
     await snapshot(<Dashboard />, "/");
   });
+  it("Dashboard deep link opens the Workflow sub-tab with the workflow analytics", async () => {
+    localStorage.removeItem("dashboard_tab");
+    const { container } = render(
+      <MemoryRouter initialEntries={["/?tab=analytics&sub=workflow"]}>
+        <Dashboard />
+      </MemoryRouter>
+    );
+    await settle();
+    const headings = [...container.querySelectorAll("h2")].map((h) => h.textContent);
+    expect(headings).toContain(i18n.t("workflows:title"));
+  });
   it("Sessions", async () => {
     await snapshot(<Sessions />, "/sessions");
   });