feat(ci): add arm64 snap build and update CI dependencies}
- Add new snap-arm64 job to build workflow for native arm64 snap builds on ubuntu-24.04-arm runner with Snap Store upload - Update actions/checkout from v4 to v5 - Update actions/setup-node from v4 to v6 - Pin softprops/action-gh-release to v2.5.0 with fail_on_unmatched_files and overwrite_files options enabled - Add top-level permissions (contents: write) to build workflow - Switch from secrets.GITHUB_TOKEN to github.token for release uploads - Fix YAML indentation in Windows publish job - Remove commented-out macOS certificate/signing code - Remove pull_request trigger from test workflow - Bump version to v2026.4.120 - Add changelog entry for arm64 snap build support