feat: add volunteer mailing list page and update volunteer links to n…

[Nguyen-HanhNong]

🎯 Overview

This PR implements a dedicated volunteer mailing list signup page and updates the volunteer page links to use the new internal form instead of external Google Forms.

✨ Changes Made

• New volunteer mailing list page (/volunteer-mailing-list/) with comprehensive form including volunteer interest categories, form validation, and responsive design
• Updated volunteer page links to point to the new internal form instead of external Google Forms
• Fixed typo: "oppurtunities" → "opportunities" on the volunteer page

�� Technical Details

• Created new volunteer-mailing-list.html template with form validation and Google Form integration
• Added new content file content/volunteer/mailing-list/index.md for the page
• Updated layouts/_default/volunteer.html to link to the new form
• Form includes 8 volunteer interest categories with "Other" option and proper validation
• Maintains existing Google Form data collection while providing better user experience

[MathyouMB]

@Nguyen-HanhNong

Is the google form component potentially private?

I seem to get the following when I add a name, email and one selection:

[Nguyen-HanhNong]

I thought we were removing the Google Form component with the change. I just removed the access to the links in the CCSS website with my change.

[Nguyen-HanhNong]

as discussed at the weekly meeting, I'll wait on Landon to setup the Octopus email before continuing on with this PR.