Read listening metric trends

Requires an active agency user with Listening access and access to the client. Reads stored data only; never starts collection or AI generation. Dates are inclusive UTC days (YYYY-MM-DD), at most 400 days; omitted dates default to seven days ending yesterday. Array query parameters are comma-separated. compare=false disables the previous-period comparison. segment selects public posts, owned channels or both (all, the default). Brand insights always apply the brand entity scope. Post previews are limited to 500 characters; cursor is a nonnegative offset and must be reused with unchanged filters. Saved workspace findings retain their own evidence windows. Missing measurements remain unavailable.