ProfileOrganizerItem.user_id typed as string, backend sends number

## Bug Frontend `ProfileOrganizerItem` types `user_id` as `string` but backend sends `int`. ## Impact - `===` equality checks fail silently (e.g., `organizer.user_id === currentUser.id` is always false) - React key warnings or collisions when using user_id as key - Any lookup/comparison involving organizer user_id breaks ## Fix Change frontend type from `user_id: string` to `user_id: number`. ## Location - Frontend: `features/organizations/api/organizations.profile.api.ts` → `ProfileOrganizerItem` - Backend: `app/schemas/organization.py` → `ProfileOrganizerItem.user_id: int` ## Found by API contract audit (2026-03-19)