chore: add basic github workflow

[achou11]

Towards #56

Introduces a basic github action that runs on non-draft PRs. Currently only does typechecking for both backend and frontend.

Does the following checks for now:

• all: formatting checks
• backend: type checks
• frontend: unit tests

ESLint (for all) and typechecking (for frontend) to be done as a follow-up

[EvanHahn]

Totally subjective, but: I think we should merge this such that CI passes, even if the tests are incomplete. I would do this by running npm run lint:prettier and npm test (which pass) instead of lint:types.

Later, we should fix types & ESLint, then enable them in CI.

Just my opinion. I think this approach is also reasonable.

[achou11]

I would do this by running npm run lint:prettier and npm test (which pass) instead of lint:types.

any thoughts on running prettier in a separate job, since it applies to both frontend and backend? currently laid out such that there are separates jobs for backend and frontend checks.

[EvanHahn]

any thoughts on running prettier in a separate job, since it applies to both frontend and backend?

No preference as long as there's no way for Prettier mistakes to slip through. Maybe a separate job for tasks that apply to both?

[achou11]

there's probably a way to de-duplicate some of the setup steps that are shared by these jobs but can look into it as a follow-up

note to self: look into composite actions