Fix v2 sync

[josephjclark]

Short Description

Fix v2 GH deploy

Fixes #1422

Implementation Details

I've been trying to fix this on the assumption that the API key was somehow not being set on redirect.

But that's wrong! The problem actually is the endpoint.

This PR:

• refactors the redirect code to be cleaner and easier to manage
• Fixes tracking of endpoint through pull and deploy
• Adds unit tests on pull to ensure that endpoint is set
• Adds an integration test for deploy

Testing this stuff is so hard and I'm paying the price of not having better testing earlier. I've added a few new tests here to try and cover us. I'd really like to spend a day on this, but can't justify it.

AI Usage

Please disclose whether you've used AI anywhere in this PR (it's cool, we just
want to know!):

• I have used Claude Code
• I have used another model
• I have not used AI

You can read more details in our
Responsible AI Policy

[josephjclark]

I'll have to test this against sync in production:

• Can pull in v1
• Can commit and deploy in v1
• Can pull in v2
• Can commit and deploy in v2

[josephjclark]

v2 still fails to deploy :(