feat: Swagger docs for `/pay` endpoints #3023

Job	Run time
Check file changes	7s
Run Integration tests	5m 20s
Run API Tests	1m 55s
Build React App	6s
E2E tests	9m 21s
Run React Tests	0s
Generate Hasura Change Summary	0s
Upsert Vultr Instance	10m 14s
Run Pulumi Preview	0s
Run Healthcheck on Pizza Services	0s
	27m 3s

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