fix: require Node.js 24 for native updater

[carbon-teq]

Summary

• require Node.js 24 or newer in deb, RPM, and pacman updater packages
• execute the packaged system runtime at /usr/bin/node so user version-manager shims cannot select an older Node.js
• keep the Debian update-manager service alive during self-upgrades so successful promotion state is recorded
• document the Node.js runtime requirement in English, Chinese, packaging, updater, and changelog documentation

Validation

• cargo test -p codex-update-manager: 50 passed
• cargo clippy -p codex-update-manager --all-targets -- -D warnings
• node --test scripts/lib/package-common.test.js: 12 passed
• bash syntax and git diff checks
• built and installed codex-desktop 2026.08.31.172424 on Pop!_OS
• verified nodejs 24.20.0, active updater service, signed upstream metadata check, idle status, and no updater error

[ilysenko]

Thanks for improving native updater reliability. Two issues block this change:

1. Skipping the Debian service stop leaves the old executable running after replacement. current_exe() then returns a path ending in (deleted); builder.rs passes it as UPDATER_BINARY_SOURCE, and ensure_updater_binary rejects the next rebuild. I reproduced this with the real packaging helper. Please move the independent Debian lifecycle change, its test and documentation to a subsequent PR. That fix needs safe process refresh after state persistence and a regression test covering the next rebuild.
2. Requires: nodejs >= 24 does not enforce the runtime floor on Fedora: its epoch-1 Node 22 package satisfies this dependency, while the updater rejects /usr/bin/node 22. Make the dependency and selected runtime consistent across supported RPM distributions, with coverage rejecting Node 22 and accepting supported Node 24 providers. Do not assume a single epoch across distributions.

Please run the complete updated base-to-head diff through your own code-review model, fix every blocker it finds, rerun the review, and repeat until it reports no remaining blockers before requesting maintainer re-review.