UI: internationalize hardcoded strings in admin `health.tsx`

[JustinaChano04]

Area: admin-dashboard/ · Difficulty: easy

Problem

admin-dashboard/pages/health.tsx still renders hardcoded English copy (for example Control-plane health, Re-run, All systems healthy, and No report available.) instead of using the admin i18n hook. That makes the health page inconsistent with the localized admin surfaces and leaves it untranslated when the operator switches locales.

Scope

Import useI18n from admin-dashboard/lib/i18n and wrap the page's user-facing strings in t(), following the same pattern used by localized admin pages such as members.tsx and the existing queue i18n issue. Keep this scoped to text/i18n wiring only — no data-flow or layout changes.

Acceptance

• Switching the admin locale away from English updates the visible health.tsx strings.
• The page behavior, polling, and status rendering stay unchanged.
• cd admin-dashboard && npm run typecheck passes.

Why this is a good first issue

Single-file UI cleanup with a clear pattern to copy, visible before/after verification, and no backend or state-management risk.

[solomon2773]

Thanks @JustinaChano04 — I checked current master and confirmed health.tsx still bypasses the admin i18n layer. The scope and acceptance criteria are accurate, so this remains open and unassigned as a good first issue. A contributor can claim it in this thread before starting. Please keep the PR to text wiring, include a screenshot in at least one non-English locale, and report the admin-dashboard typecheck.