Add E2E testing before deployments to main

[natesabrown]

Want some basic UI testing (possibly unit tests, but that's not as important to me atm) to ensure stuff can be loaded and tapped, etc. before deployments.

[natesabrown]

Going to probably add Cypress UI testing as a bare minimum to make sure certain parts of the UI are available after changes. Will look into options for running them before deployment.

[natesabrown]

Changed this to reflect a broader CI purpose for this if we can ever get around to it