Add Search Console Property

Adds a website as a property to the connected Search Console account, so a site that was never added (gsc_list_sites does not show it) can be set up from chat. `site_url` is either a domain property ('sc-domain:<domain>', covers every subdomain and http/https) or a URL-prefix property ('https://www.<domain>/'). A newly added property is UNVERIFIED: Google only shows its data after ownership is proven, and the verification code is shown only to the signed-in owner in Search Console. Next step after adding: the user opens the property in Search Console (link in the result), picks the DNS TXT method, and gives you the 'google-site-verification=...' value; if the domain's DNS is hosted on Opus Growth, write it with site_dns_records (mode='add', type='TXT') and the user presses Verify. confirm=false previews, confirm=true adds.