ci: force Actions JavaScript runtime to Node 24

[jeevanpillay]

Summary

• Add FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true to the ci job in ci.yml
• Add the same env var to the release job in release.yml
• This opts GitHub JavaScript actions into Node 24 now to avoid upcoming Node 20 runtime deprecation impact

Context

• No open PRs or issues were found in lightfastai/climode
• Historical failing runs from April 2, 2026 were investigated
• The prior pnpm build failure (Duplicate package name) is already resolved on main by commit ad7325b

Verification

• pnpm build passes locally on main before this workflow-only change
• Workflow changes are scoped to two YAML files only