fix: Linux release glibc compatibility

[0dragosh]

Summary

Fixes #45

Build Linux release artifacts on Ubuntu 22.04 instead of ubuntu-latest so the published GNU binaries stay compatible with Ubuntu 22.04 / glibc 2.35 environments.

Root Cause

The release workflow was building x86_64-unknown-linux-gnu and aarch64-unknown-linux-gnu artifacts on ubuntu-latest, which can link against a newer glibc than Ubuntu 22.04 provides. That makes cargo-binstall installs fail at runtime with errors like GLIBC_2.39 not found.

Changes

• pin Linux release asset jobs to ubuntu-22.04
• add an integration test that fails if those GNU targets drift back to ubuntu-latest

Validation

• cargo test --locked test_release_linux_binaries_target_ubuntu_22_04
• nix develop -c cargo fmt --all -- --check
• nix develop -c cargo clippy --locked --all-targets -- -D warnings

Notes

cargo test --locked --all-targets still fails on this nix-darwin machine in three pre-existing hook integration tests unrelated to this workflow change:

• test_hooks_install_adds_managed_hook_even_with_other_cwt_like_command
• test_hooks_install_patches_settings_json
• test_hooks_install_idempotent