[codex] Expand i18n coverage across main surfaces

From the PR description

Summary

• Move the language switcher from the sidebar account menu into the Account settings profile section below email.
• Add catalog-backed translations for assistant chrome, account settings, projects, tabular reviews, workflows, and related modals.
• Extend all supported locale catalogs (en, pt, es, fr, de) with matching keys for the new translated surfaces.

Why

The i18n rollout left several high-visibility app surfaces with hardcoded English strings. This makes locale switching feel incomplete across the main lawyer-facing workflow.

Validation

• npm run lint:catalogs --prefix frontend
• npm test --prefix frontend (55/55)
• npm run build --prefix frontend
• docker compose --env-file .env.docker up -d --build frontend
• curl -I -sS http://localhost:3000/login | head returned 200 OK

Notes

• Built-in workflow/legal prompt text remains untranslated because it is domain content, not app chrome.
• Full repo npm run lint --prefix frontend still fails on existing unrelated lint debt; this PR was validated with catalog tests, frontend tests, and production build.