New features: Monorepo support

## New Feature Ideas

### Monorepo support

```yaml
# Support for workspaces within repos
repositories:
  - name: monorepo
    url: git@github.com:org/monorepo.git
    workspaces:
      - path: packages/api
        tags: [backend]
      - path: packages/ui
        tags: [frontend]
```
