deploy: add Dockerfile + nginx config for static hosting

The web/ directory is fully self-contained (index.html + worklet.js, all JS
deps pulled from esm.sh via the importmap). Package it as a tiny nginx:alpine
image so Coolify can build + serve it behind Caddy.

- Dockerfile: nginx:1.27-alpine, copies web/ to the document root, healthcheck.
- nginx.conf: serves /, no-cache for index.html and worklet.js (so engine
  changes land immediately after a redeploy), short cache for everything else,
  gzip on text payloads, JS MIME for AudioWorklet.
- .dockerignore: keep the image small (excludes Python sources, docs,
  references, sandbox is included since it's served from /sandbox/).

Dockerfile

@@ -0,0 +1,14 @@
+# code-sinth — static site served by nginx
+# The web/ folder is fully self-contained (index.html + worklet.js).
+# All JS dependencies are loaded from esm.sh via the importmap.
+FROM nginx:1.27-alpine
+
+# Replace the default nginx site config with one that serves /web/ at /,
+# applies long cache for the worklet, and sets the right MIME types.
+RUN rm /etc/nginx/conf.d/default.conf
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+COPY web/ /usr/share/nginx/html/
+
+EXPOSE 80
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+  CMD wget -qO- http://localhost/ >/dev/null || exit 1