The ASC API's 3-step review submission flow (and why appStoreVersionSubmissions is gone)

I spent yesterday automating app submissions for 4 iOS apps. Straightforward task: hit an endpoint, POST the app version to App Review, done. Except the endpoint I was reaching for — /appStoreVersionSubmissions — is deprecated. Apple's replaced it with a three-step choreography using /reviewSubmissions. No official migration guide. Just a quiet documentation update and broken automation scripts all over GitHub. Here's the flow, with working curl examples. The old way (dead) cur...