[Frontend] Add public emergency-profile cache-control policy

## Problem
Public emergency pages may be cached by browsers, CDNs, or service workers beyond the profile owner’s intended lifetime.
## Acceptance criteria
- Emergency responses use explicit cache headers based on revocation/expiry semantics.
- Authenticated and public data never share a cache key.
- Service-worker behavior is tested for revoked and expired profiles.
- Tests verify no sensitive response is stored in browser caches.

Start by locating the frontend emergency-response entry points and the service-worker code that controls caching. Trace how public and authenticated responses are keyed and how revocation or expiry is represented. Done means explicit cache policy is applied, public and authenticated data cannot share keys, revoked and expired profiles are covered by service-worker tests, and sensitive responses are not stored.

Written by the indexing model from the issue text.