[App Portal - Feature] Portal Config Page

Admin users should have the ability to configure the application portal opening dates, closing dates, RSVP windows etc. 

<img width="1617" height="952" alt="Image" src="https://github.com/user-attachments/assets/a3513714-1965-4173-875f-f8b53b89dadc" />

Create this view in the Admin Page, and create the functionality to update these different windows and dates. All dates are stored in Mongo. 