Fetch jwt instead of hardcoding vapi api key

[mikejonas]

I set up an api route to issue a temporary jwt that's signed by the vapi api key, so we don't hardcode the keys into the app. In the App, Before starting a call, it fetches a new jwt and starts the call with that.

I used Supabase for the api, since it's easy, but open to moving to something else if we need, or if anyone wants to.

issue-vapi-token api route (We should Setup a github organization for her, so that way can have an ios repo and a backend repo.)

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I'm not used to working in swift, so if anything doesn't look right in the code, let me know.

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Follow up plans:

• If we're going to open source this, as a follow up we can set it up so devs can still enter their vapi api key, instead of using a backend route for local development.
• It would also be nice to have a swift equivalent of a .env file, for the api url or anything else like that. That way it's easy switch back and forth from localhost or prod server

[mikejonas]

I'll redo this since it's dated and there's merge conflicts