fix(e2e): restore the frontend build by typing the responses findOrFail searches (#254)

main did not build, so every Portainer deploy failed with `npm run build` exit code 2. My regression from #241.

findOrFail<T>(items: T[], predicate: (item: T) => boolean) infers T from both parameters. The call sites annotate the predicate as documentation, and the arrays come from .json(), which is any and offers no competing candidate — so T became the one-field shape written in the lambda and every caller failed on the field it actually wanted. Array.prototype.find has no such problem, which is why the code this replaced type-checked.

The four responses are now typed at their call sites, so T is inferred from real data and the predicates need no annotation. findOrFail additionally takes NoInfer<T> on its predicate, so a stray annotation can never drive the element type again. The specs are better typed than before this change: `.json()` was plain any, and the annotations only ever documented a shape nothing enforced.

I did not catch this because I verified with a bare `npx tsc --noEmit`, and tsconfig.json is `"include": ["src"]` — it structurally cannot see tests/. The specs are checked by the second command in `npm run build`, which is the step Docker runs and the step that failed. Verified this time with `npm run build` itself, plus lint, the unit suite, and two consecutive full e2e passes.

Closes #254

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

frontend/tests/e2e/admin-taxonomy.spec.ts

@@ -40,10 +40,12 @@ test.describe('Admin taxonomy', () => {
 
     // The table paginates and the shared database holds many tags, so the new
     // row is confirmed through the API rather than hunted for across pages.
-    const tags = await (await page.request.get('/api/admin/tags')).json();
+    const tags: { name: string; color: string | null }[] = await (
+      await page.request.get('/api/admin/tags')
+    ).json();
     const created = findOrFail(
       tags,
-      (tag: { name: string }) => tag.name === `vintage-${RUN}`,
+      (tag) => tag.name === `vintage-${RUN}`,
       `the tag vintage-${RUN}`
     );
     expect(created.color).toBeTruthy();