Browser-based login via OAuth for Notehub CLI

[scottfrazer]

Requires this PR to be deployed: https://github.com/blues/hub/pull/6680.

In order to test this locally, build the notehub binary from this branch with cd notehub then go install. Then, deploy the code in the hub PR mentioned above.

Run a notehub -hub preprod.blues.tools -signin

A browser window should pop up prompting you to login, then the CLI should print:

$ notehub -hub preprod.blues.tools -signin
Opening web browser to initiate authentication (redirect port 58766)...
             _       _           _
            | |     | |         | |
 _ __   ___ | |_ ___| |__  _   _| |__
| '_ \ / _ \| __/ _ \ '_ \| | | | '_ \
| | | | (_) | ||  __/ | | | |_| | |_) |
|_| |_|\___/ \__\___|_| |_|\__,_|_.__/


signed in as sfrazer@blues.com
token expires at 2025-09-24 21:05:34 EDT

Jira Ticket: TS-719

[rayozzie]

Really well-done and well-packaged. I can see now that what I'll do in the notebook utility (which will need signin) is to bind to note-cli/lib. The way you structured it looks great.