Injects a PSP SDK <script> once per page (idempotent via DOM lookup) and
resolves on load. A load failure rejects with a retryable psp_unavailable
attributed to pspName. Adapters keep their own poll-for-global logic —
this only gets the script tag onto the page.
Injects a PSP SDK
<script>once per page (idempotent via DOM lookup) and resolves on load. A load failure rejects with a retryable psp_unavailable attributed topspName. Adapters keep their own poll-for-global logic — this only gets the script tag onto the page.