Linux release binaries require glibc >= 2.38

Found verifying the 0.1.0 release, pre-existing since rc.1: Linux binaries are built on ubuntu-latest (24.04, glibc 2.39) and require glibc >= 2.38. They fail on Debian 12 bookworm (2.36) and Ubuntu 22.04 LTS (2.35) with:

```text
beam.smp: /lib/x86_64-linux-gnu/libc.so.6: version 'GLIBC_2.38' not found
```

The cherry-dev image itself (bookworm) cannot run its own release binary. Fix: pin the Linux release-build jobs to older runners (or an older-glibc container) so the floor drops to something Debian-stable users have. Candidate for a 0.2.1 patch release; needs a CI assertion on the resulting binary's glibc floor so it never regresses.

Start by locating the Linux release-build jobs in the CI configuration and reviewing how the cherry-dev image runs the release binary. Rebuild with an older runner or glibc environment, verify the binary runs on Debian 12 and Ubuntu 22.04, and add a CI assertion that catches a higher glibc floor.

Written by the indexing model from the issue text.