chore: migrate open issues to new label taxonomy #692

Part of #690

Go through all 79 open issues and apply the new label taxonomy.

For each issue

1. Add kind/* (required)
2. Add area/* (at least one)
3. Add priority/*
4. Remove old labels
5. Add status/accepted if triaged, or status/needs-info if waiting on author

Mapping reference

Target: all open issues labeled within one pass.