NL-02 fixes: drop CNAME (Workers Custom Domains manage DNS), fix path encoding, add tests

- Remove cfEnsureProxiedDns from admin route — Workers Custom Domains auto-manage DNS records - Remove CNAME step from deploy script — same reason; also remove unused node:fs imports - Fix worker script: don't encodeURIComponent the domain in /p/{domain} path (Next.js expects raw) - Add vitest + 16 tests: hostname extraction (multi-part TLDs), worker script assertions, sitemap host logic