feat(web): i18n with react-i18next (sv/en)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/test/setup.ts

@@ -3,6 +3,24 @@ import { afterAll, afterEach } from "vitest";
 
 import { server } from "./server";
 
+// Node v26 does not expose localStorage as a global unless --localstorage-file
+// is passed. Provide a minimal in-memory shim so i18n and other modules that
+// call localStorage.getItem/setItem work in jsdom tests.
+if (typeof globalThis.localStorage === "undefined") {
+  const store: Record<string, string> = {};
+  Object.defineProperty(globalThis, "localStorage", {
+    value: {
+      getItem: (key: string) => store[key] ?? null,
+      setItem: (key: string, value: string) => { store[key] = value; },
+      removeItem: (key: string) => { delete store[key]; },
+      clear: () => { Object.keys(store).forEach((k) => { delete store[k]; }); },
+      get length() { return Object.keys(store).length; },
+      key: (i: number) => Object.keys(store)[i] ?? null,
+    },
+    writable: true,
+  });
+}
+
 // Start MSW at module level so its fetch patch is in place before any test
 // module captures globalThis.fetch via openapi-fetch's createClient().
 server.listen({ onUnhandledRequest: "error" });