feat: add fullstack capstone project demo

[Ksound22]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Closes #XXXXX

[jdwilkin4]

Just started testing this locally and noticed there wasn't a place to toggle a show/hide password for the signup page.

I think that should be added as a nice UX improvement and is a common pattern for forms.

[jdwilkin4]

To me this Invalid request data. banner at the top when you fill out the form incorrectly isn't needed.

You are already showing validation error messages next to the fields which should be enough.

[jdwilkin4]

The second Profile text here isn't needed.

[jdwilkin4]

I created an org and noticed this toggle at the top.
Not sure what it does but it looks like a bug to me.

toggle-collaborer.mov