i18n: extract strings — settings

[Davidnet]

Part of the frontend internationalization effort (see Epic). Depends on the infra issue.

Files

• src/frontend/src/components/settings/ProvidersSection.tsx (~626 lines)
• src/frontend/src/components/settings/PIISection.tsx
• src/frontend/src/components/settings/AdvancedSection.tsx
• src/frontend/src/components/settings/CertificatesSection.tsx
• src/frontend/src/components/settings/SettingsView.tsx

Use the settings namespace.