Update an existing element by `type` and `id`, changing ONLY the fields you
pass — omitted fields are preserved.
This is a server-side read-merge: the current element is loaded and only the
keys in `fields` are applied, so it is safe against the raw-HTTP-PATCH hazard
where sending a partial link array replaces the whole array. Semantics per field
kind: a text field you pass is set (pass an empty string `""` to clear it); a
multi-link field you pass REPLACES that field's array wholesale (pass an empty
array `[]` to clear it) — for additive/subtractive link edits that leave the
rest of the array intact, use `edit_links` instead. `type` is a slug from
`list_element_types`; `id` is the element's UUID. Requires a WRITE API-Key.
Returns the full updated element in the v2 wire shape. Errors if the element
does not exist, or (naming the field) on an unknown field or a bad link target.
Connector