Add test cases for internationalization, orders table rendering, and error handling:

- **Internationalization:** Added end-to-end test `i18n.smoke.spec.ts` to validate Danish locale translations. Ensured normalization and removed unexpected strings in the `da` locale file.
- **Orders Table:** Created unit test `orders-table.spec.js` to verify sparse data handling, invoice collection preloading, and rendering correctness.
- **Error Handling:** Enhanced connectivity issue UI (`ConnectivityIssue.vue`) with `data-testid` attributes for improved testability.
- **E2E Playwright Tests:** Updated and simplified e2e test utilities. Replaced `seedAuthenticatedState` with `primeMockSession` for session preparation. Added new tests for `/user/orders` and `/user/invoices` pages focusing on edge cases and maintaining structure consistency.

tests/e2e/superuser-system-status.smoke.spec.js

@@ -1,5 +1,5 @@
 import { expect, test } from "@playwright/test";
-import { mockApi, seedAuthenticatedState } from "./support/network.js";
+import { mockApi, primeMockSession } from "./support/network.js";
 
 function json(body, status = 200) {
   return {
@@ -11,16 +11,7 @@ function json(body, status = 200) {
 
 async function primeSuperuserSession(page) {
   const token = "superuser-system-status-token";
-  await seedAuthenticatedState(page, token);
-  await page.goto("/login");
-  await page.evaluate(async (sessionToken) => {
-    const sessionModule = await import("/src/components/session/token/SessionUser.vue");
-    window.localStorage.setItem("token", sessionToken);
-    sessionModule.SessionUser.token.value = sessionToken;
-    sessionModule.SessionUser.authenticated.value = true;
-    sessionModule.SessionUser.permissions.value = ["superuser", "user"];
-    sessionModule.SessionUser.initiated.value = true;
-  }, token);
+  await primeMockSession(page, { token });
 }
 
 async function installSystemStatusMock(page, snapshot) {