GET /api/activity/reports/risk/groups/

Return the organization's groups with an activity policy assigned, ranked by high-risk prevalence: the percentage of each group's tracked members (any activity in the window) whose advisory risk score is High or Critical, with the highest member score as secondary detail. Members with no activity in the window are left out of the denominator, a member in several groups counts in each, and a group under five tracked members has a null high_risk_percent and sorts last. Group membership is resolved at request time, over the same fixed rolling 30 days as the member scores. Optional groups narrows the rows to those groups. Restricted to organization admins/managers or activity & security report viewers, and gated by both the activity-tracking and risk-scoring flags.