Add environments to a projectUNLEASH_ADD_ENVIRONMENTS_TO_PROJECT
Sequentially associate multiple environments with one project after rejecting duplicates and existing associations. On the first failure, attempts to remove only additions acknowledged during this run in reverse order. This is a non-atomic compensating workflow that can execute deletions; the response reports forward progress, cleanup attempts, cleanup failures, and possible partial state. A definitive 4xx rejects the failed item, while a 5xx or transport failure leaves that item's outcome unknown because Unleash may have committed it.