Build the homepage: project cards grouped in 4 sections

Replaces the placeholder index.html with a full personal-projects page
listing all 17 projects across four sections (CipherDolls, decentralized
apps, AI on GPU, Ethereum infrastructure) as cards with name, description,
tech tags, and GitHub links. Adds styles.css (dark-first, light override,
mobile-first responsive grid) and a .dockerignore to keep the build context
clean. Updates the Dockerfile to copy styles.css alongside index.html.

Dockerfile

@@ -3,7 +3,7 @@ FROM nginx:1.27-alpine
 LABEL org.opencontainers.image.title="ffaerber/homepage" \
       org.opencontainers.image.source="https://git.ffaerber.duckdns.org/ffaerber/homepage"
 
-COPY index.html /usr/share/nginx/html/index.html
+COPY index.html styles.css /usr/share/nginx/html/
 
 EXPOSE 80