Support for VS Code Workspaces

### Describe the feature or problem you'd like to solve

Agency will only find agents/skills on the current folder, but not in subfolders

### Proposed solution

I have projects that are multi repo: several different repos and my own folder of agents/skills. Using VS Code Workspaces it is trivial to setup VS Code to open all the repos and my folder of agents/skills and have the Github Copilot Chat aware of all the agents/skills.

Currently, I can't replicate this with agency: I can't start agency from a workspace file, and if I open the root folder containing all projects, agency only finds agents/skills on the folder it opens, not in any subfolders.

### Example prompts or workflows

_No response_

### Additional context

Example of a workspace file, my .github with my agents/skills is under the agentic-design folder.

{
"folders": [
{
"name": "agentic-design",
"path": "."
},
{
"name": "Engine",
"path": "../Babylon.js"
},
{
"name": "Documentation",
"path": "../BabylonDocumentation"
}
],
"settings": {}
}