List the activity policies that apply to a user via their group memberships.

Resolves the same "which policies apply to this member" question the Admin Console member-detail screen answers, but keyed on a user id for support triage — each row carries the policy's assigned_groups (all groups it's assigned to) and matching_groups (the subset the user belongs to that make it apply). Spans every organization the user has an applicable policy in; organization on each row disambiguates. Soft-deleted memberships are excluded (group_ids reflects active memberships only).