Add full shell, replaceable Omics adapter and bilingual interaction

Implement approved specification #32 and tickets #33-#37. Keep host authentication server-verified and pin session interaction language. Compile scoped base selectors for browser compatibility and retain full gutters during CSS pruning.

frontend/src/shell/PiManagement.test.tsx

@@ -1,4 +1,5 @@
-import { render, screen, waitFor, within } from "@testing-library/react";
+import { act, render, screen, waitFor, within } from "@testing-library/react";
+import { setLocale } from "../i18n";
 import userEvent from "@testing-library/user-event";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { http, HttpResponse } from "msw";
@@ -13,6 +14,20 @@ const readyStatus = {
   checkedAt: "2026-08-05T10:00:00.000Z",
 };
 
+test("updates Pi controls and host instructions when the locale changes without remounting", async () => {
+  renderManagement(true);
+  await screen.findByRole("button", { name: "Test catalog default" });
+  try {
+    act(() => setLocale("it"));
+    expect(screen.getByRole("button", { name: "Verifica il modello predefinito del catalogo" })).toBeVisible();
+    await userEvent.click(screen.getByRole("button", { name: "Manutenzione host" }));
+    expect(screen.getByRole("heading", { name: "Apri la directory del progetto" })).toBeVisible();
+    act(() => setLocale("en"));
+    expect(screen.getByRole("heading", { name: "Open the project root" })).toBeVisible();
+    expect(screen.getByRole("button", { name: "Runtime and models" })).toBeVisible();
+  } finally { act(() => setLocale("en")); }
+});
+
 function renderManagement(page = false) {
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
   return render(