UI preview policy

Only two legacy simulated previews are retained as narrow visual references. They were generated with injected HTML/CSS/JS and simulated API/fetch/storage, so they are not current Rust runtime evidence and may differ from the 0.22.3 UI. Runtime verification status belongs in ../TEST_REPORT.md.

login.png: anonymous minimal Polish login document.
location-headers.png: request/response rules for an individual location.

RustProxy 0.19.1 removes the other old simulated screenshots so stale layouts are not presented as current product state.