Set up Astro with GitHub Pages and migrate homepage from `new-homepage` branch

[pmcelhaney]

Description

We want to move this site to Astro and deploy it via GitHub Pages, using the existing index.html from the new-homepage branch as the foundation.

This should be done in a way that preserves the current homepage content while setting us up for future expansion (docs, additional pages, etc.).

Goals

• Set up an Astro project in this repo
• Configure deployment to GitHub Pages via GitHub Actions
• Convert the existing index.html (from new-homepage) into an Astro layout/template
• Use the existing homepage content as the site’s root (/)

Requirements

1. Astro setup

• Initialize Astro in the repo
• Use minimal setup (no unnecessary integrations)
• Ensure the project builds to static output

2. GitHub Pages deployment

• Add a GitHub Actions workflow to:
  • Install dependencies
  • Build the Astro site
  • Deploy to GitHub Pages
• Use the official GitHub Pages action (no custom hacks)
• Ensure this works for the default branch

3. Homepage migration

• Pull index.html from the new-homepage branch
• Convert it into an Astro layout (e.g., src/layouts/MainLayout.astro)
• Preserve:
  • Structure
  • Styles
  • Scripts (only if necessary; prefer removing anything non-essential)

4. Home page

• Create src/pages/index.astro
• Use the layout created above
• Move the content from index.html into this page
• The rendered output should closely match the current homepage visually

5. Asset handling

• Ensure any referenced assets (CSS, JS, images, fonts) are:
  • Moved into appropriate directories (public/ or src/)
  • Properly referenced in Astro

Constraints

• Do not introduce a heavy framework (no React/Vue unless required)
• Keep things simple and easy to understand
• Prefer static-first approach (minimal client-side JS)

Acceptance Criteria

• Running npm run build produces a static site
• GitHub Actions successfully deploys to GitHub Pages
• Visiting the site shows the same homepage content as new-homepage/index.html
• Code is clean and easy to extend for additional pages

Manual Acceptance Tests

• Clone repo, run npm install and npm run dev, verify homepage renders correctly
• Run npm run build and preview output, verify no broken assets
• Confirm GitHub Pages deployment succeeds via Actions
• Visit deployed site and confirm visual parity with original index.html

If anything is ambiguous, prioritize simplicity and preserving the current homepage experience.