Add the ability for parallel workflows to trigger linear workflows

[Velora]

• Each prompt in a parallel workflow can optionally trigger a linear workflow.
• A UI is provided to write the filename of a linear workflow md file on any prompt in the workflow editor.
• This allows the user to create more powerful workflows and reuse linear workflows in a modular way.

[jcollingj]

@Velora This is awesome! Love the idea. Most of the code looks good to me, but there are a few pieces I'd like to have smoothed out before merging it in.

Could you:

• For the Workflow Editor view:

  • Change it so the "trigger linear workflow" option only displays if the workflow being edited is a parallel workflow
  • Add validation so a user can't add a non-linear workflow file. We can keep this simple and just validate it on save. You should be able to use getFrontMatter to check if the given file is a linear workflow or not.

• Not 100% sure, but I think there is also a bug in triggering the linear workflow. I attached two screenshots here of me trying to use it. Maybe there is an issue with parsing the spaces of the file name? I've confirmed it's a parallel workflow attempting to execute a linear one. Although the extra validation above would really help with that too.

And thank you again for the PR here! Would absolutely love to get this integrated!

[Velora]

Glad you like it. I can look at this, but it may not be until the weekend.

I agree on the proposed changes.

Re: The bug of not triggering, it could be an issue parsing the spaces. I came across a potentially separate bug where created linear workflows would show "undefined" as a value for the "caret_prompt" property instead of "linear", and I had to manually set the property to "linear" on the file.