Flaky update detection through socket.io

[mtlynch]

Description

Users who upgrade from pre 975a64a to post 975a64a will see the "Restarting to complete update" spinner forever.

This is because 975a64a upgraded the client and server to use a version of the socket.io protocol that is not backwards-compatible with previous clients. After the update, the server has the new version of the protocol, but the JS client still has the old version until they reload the page.

We should switch to an HTTP-based solution (e.g., querying GET /api/status). HTTP is much less likely to have version incompatibilities no matter what library we update to.

What's the behavior that you expect?

Update completes successfully.

What's happening instead?

Update hangs on the waiting for restart page.

What are the steps to reproduce this behavior?

1. Install TinyPilot 1.4.0
2. Click on System > Update
3. Proceed with the update prompts