Save through an edit-mode share link (no auth)

Anonymous save path for edit-mode share links: same optimistic rev contract as the authenticated save (409 carries the current server doc). View-only links get 403. Wiki-link syncing is skipped and last_edited_by is left untouched.

curl -X PUT "https://example.com/v1/public/pages/string/doc" \  -H "Content-Type: application/json" \  -d '{    "doc": {},    "rev": 0  }'

{  "rev": 0,  "updated": "2019-08-24T14:15:22Z"}