fix: prevent unintended escaping of multiline run

[kazutoiris]

Fix #2257 - When generating GitHub Actions workflows, multi-line commands in run blocks were being automatically escaped with quotes, causing command not found and execution failures.

Before

Renders with unintended quotes inside a multi-line block

- name: "Build assets"
  run: |
    "npm run build"  # ← Quotes break command execution

After

Single-line commands should render as inline strings without quotes

- name: "Build assets"
  run: |
    npm run build

[mistydemeo]

Good catch, thank you!