another issue tagging pass, release plans

[Greg Troxel]

I just went over the issue tracker and pinged a bunch, closed a few,
converted one to discussion. (My take is that questions belong in
discussions, and that device decoder issues are ok if they are part of a
path to getting a decoder in the sources.)

I also closed the 'release is overdue' issue, which was overdue for
closure since February. But I opened a new issue that a release is due
in 2025.08, because I am making up 6 months.

I propose that we go into feature freeze on 2025-08-01, ask everyone to
update and test and release on 2025-08-08 if no prolems, otherwise
address issues.