Add FUNDING.yml for GitHub Sponsors

## What
The main `cognitiveos` meta-repo is missing a `.github/FUNDING.yml` file. All other repos in the project have one pointing to `jeanmachuca` on GitHub Sponsors.

## Why
Consistency across the project — every other repo has sponsor funding links.

## How
- Create `.github/FUNDING.yml` with:
```yaml
github: jeanmachuca
```