Remove the `v1` endpoints, only develop typed `v2`.

Change of course: instead of maintaining a faithful reproduction of the V1 API, simply develop a typed V2 API directly.
Conversion from V1 to V2 should then only be done in the tests which test that output is identical between V1 (PHP) and V2 (python), this centralizes all changes in one place and reduces (relatively minimal) overhead of developing two separate sets of API endpoints.