Mirror the backend validator.uc checks in the LuCI settings UI. Previously the validate function used validateDNS() which accepts DoH path format (e.g. 'cloudflare-dns.com/dns-query'); now we gate before that call with explicit checks matching the backend: - '://' → DoH/DoT URL (e.g. 'https://cloudflare-dns.com/...') - '/' → path-style DoH (e.g. 'cloudflare-dns.com/dns-query') Also add Russian translations for both new error messages.