Use hosted ARM runners

[bherila]

What changed

• Move ordinary GitHub-hosted CI, release, and deployment jobs from ubuntu-latest to the standard ubuntu-24.04-arm runner.
• Keep Copilot cloud-agent setup on x64 where present because GitHub currently requires an Ubuntu x64 or Windows x64 runner for that integration.

Why

The ARM runner provides the same standard private-repository capacity for these PHP and Node workflows at a lower hosted-runner rate, while also exercising ARM compatibility.

Validation

• Parsed every workflow as YAML.
• Checked the patch for whitespace errors.
• The pull-request workflow will run the project checks on ARM before merge.