#103 Testing: Admin Panel Integration Tests

Create comprehensive integration tests for Admin Panel APIs. Location: tests/integration/test_admin_panel.py Test Categories: 1. User Management Tests: - test_create_user_success - test_create_user_duplicate_email - test_list_users_pagination - test_update_user - test_delete_user_soft - test_user_permission_denied 2. Role Assignment Tests: - test_assign_role_success - test_assign_role_hierarchy_violation - test_remove_role 3. Token Management Tests: - test_generate_token - test_list_tokens - test_revoke_token - test_revoke_all_tokens 4. API Key Tests: - test_create_api_key - test_api_key_authentication - test_revoke_api_key - test_rotate_api_key 5. Invitation Tests: - test_send_invitation - test_accept_invitation - test_invitation_expiry - test_resend_invitation 6. Session Tests: - test_list_sessions - test_terminate_session - test_terminate_all_sessions 7. Audit Log Tests: - test_query_audit_logs - test_export_audit_logs All tests must use API calls only, no direct database access. With ultra attention to details and correctness. Before closing: write comment summarizing implementation with screenshot.