v0.28.1

Fixes

• IndexNow key file now serves directly, so submissions actually validate (#542). On sites with trailing-slash permalinks (the WordPress default), the /{key}.txt ownership file was 301-redirected to /{key}.txt/. IndexNow validators fetch the exact /{key}.txt and don't follow that redirect, so key validation never completed and submitted URLs were silently dropped (the submission stays at HTTP 202 "validation pending"). The key file now returns a 200 at /{key}.txt, matching the llms.txt / UCP / products.json endpoints.