Proposal: support additional system prompt

[pelikhan]

In most LLM providers, you can typically provide a system prompt vs prompt. LLM vendors do some fine tuning to make sure the instructions in the system prompt are not overriden.

Currently, we do not have a syntax to define system prompt and we do not generate system prompt.

[pelikhan]

@scout find a few alternative to specify system prompts. frontmatter vs markdown macros, etc..

[pelikhan]

Imported shared workflow should be imported as system prompts

[dsyme]

Proposal is this

---
name: something
tools: ...
---
...global user prompt...

<system>
If "${{ event.kind }}" is "assignment" then ...prompt only added for the assignment event..

If "${{ event.kind }}" is "comment" then ...system prompt only added for the assignment event..

If "${{ event.kind }}" is "assignment" or "comment" then ...system prompt used for assignment or comment..
</system>

[pelikhan]

Frontmatter section would avoid the trap of extending markdown (the NL part ) with syntax.

Counter offer to use a front matter field "system"

system:
   - ./tools.md