GroupDetail.org_id vs organization_id field name mismatch

## Bug Backend `GroupDetail` schema returns `org_id` but frontend reads `organization_id`. The ring detail page gets `undefined` for the org reference. ## Impact - Breadcrumbs to parent org broken - Navigation to org profile from ring page broken - Permission checks that reference org may fail ## Root Cause Backend `GroupDetail` Pydantic schema uses `org_id: int` (matching the DB column name). Frontend TypeScript type uses `organization_id: number` (matching the naming convention used by EventDetail). ## Fix Either: - **Backend**: Rename `org_id` → `organization_id` in GroupDetail schema (preferred — consistent with EventDetail) - **Frontend**: Rename `organization_id` → `org_id` in GroupDetail type ## Found by API contract audit (2026-03-19)