Switch static server from nginx to static-web-server

Replace nginx:alpine-slim with the scratch-based static-web-server
image, reducing the final image size ~32MB -> ~23MB (28% smaller).

- Dockerfile: serve from static-web-server:2, copy site to /public
- sws.toml: mirror previous nginx behavior (compression, cache-control,
  SPA index fallback) plus security headers and /health endpoint
- Remove now-unused nginx.conf

Dockerfile

@@ -3,8 +3,9 @@ WORKDIR /tmp/hugo
 COPY . .
 RUN hugo --gc --minify
 
-FROM nginx:alpine-slim
-WORKDIR  /usr/share/nginx/html
-COPY nginx.conf /etc/nginx/nginx.conf
-COPY --from=build /tmp/hugo/public .
+FROM ghcr.io/static-web-server/static-web-server:2
+COPY sws.toml /etc/sws.toml
+COPY --from=build /tmp/hugo/public /public
+ENV SERVER_CONFIG_FILE=/etc/sws.toml
 EXPOSE 80/tcp
+CMD ["--config-file", "/etc/sws.toml"]