#50 [Admin Panel] API Key Management - Revoke API Key

Implement DELETE /api/v1/admin/api-keys/<api_key_id> endpoint to revoke an API key. **API Specification:** - Endpoint: DELETE /api/v1/admin/api-keys/<api_key_id> - Permission Required: manage_users - Path Parameter: api_key_id (UUID) - Response: {success: true, api_key_id, revoked_at} **Requirements:** - Immediately invalidate the API key - Log audit event with key details - Cannot be undone (new key must be created) - Return 404 if key not found **IMPORTANT:** Implement with ultra attention to details and correctness. **BEFORE CLOSING:** Take screenshot showing API key revocation. Add comment summarizing implementation.