T1682, step 4

Install Cashtab dependencies.

This diff adds the dependencies required by Cashtab in one go, distinct from the generic dependencies required by the latest version of create-react-app.

cd web/cashtab-v2
nvm use 16
npm i
npm start

Observe default react screen. No Cashtab behavior is expected. Cashtab code will be dropped in according to the plan described in T1682