Add SEO metadata to all private/auth pages

[yusuftomilola]

Description:
Add Next.js metadata to all private and auth-flow pages using route-level layout.tsx files. These pages should have noindex: true to prevent search engine indexing. Pages: Reset Password, Verify OTP, Profile, Settings, Newsletter Confirm.

Acceptance Criteria:

• Each page has a unique title
• All private pages use noindex: true in metadata
• Uses existing buildMetadata() helper
• Route-level layout.tsx files return children directly

File(s): frontend/app/(auth)/reset-password/layout.tsx, frontend/app/(auth)/verify-otp/layout.tsx, frontend/app/profile/layout.tsx, frontend/app/settings/layout.tsx, frontend/app/newsletter/confirm/layout.tsx