chore(ci): generate token for supabase repo

[mandarini]

Generating token for both supabase and supabase-js repos, so that it can authenticate and trigger the workflow on the supabase/supabase repo.

This will not work yet, because:

1. The GitHub App needs to be installed on the supabase/supabase repository.
2. In the App settings, under "Repository permissions":
   • Workflows to Read and write
   • Actions to Read and write as well (optional but recommended by the github assistant)

Context: https://github.com/supabase/supabase-js/actions/runs/18308910478/job/52132648013

x-accepted-github-permissions: metadata=read

[staaldraad]

🤞🏼