Fix GitHub Pages deployment: trigger on master branch, add .nojekyll

The deploy workflow was triggering on `main` but the default branch is
`master`, so the Actions workflow never ran. GitHub Pages was also
configured with build_type=legacy (deploy from branch) instead of
workflow. Added .nojekyll to prevent Jekyll from dropping assets.

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca <noreply@eca.dev>

Author: ericdallo

.github/workflows/deploy.yml

@@ -2,7 +2,7 @@ name: Deploy to GitHub Pages
 
 on:
   push:
-    branches: [main]
+    branches: [master]
   workflow_dispatch:
 
 permissions: