Add search restore and UI validation

Add the 24-hour last-search URL restore convenience on top of the
completed search UI.

Store only the canonical generated search-route URL in a versioned
localStorage envelope, expire it after 24 hours, and restore it with
replaceState only when the current search URL has no active criteria.

Harden the UI validation script around storage isolation, URL
normalization, restore eligibility, and the search browser contract.

Author: ritorhymes