Add proper Containerfile and update Makefile to include the web shell

Containerfile

@@ -1,3 +1,20 @@
-FROM scratch
-ENTRYPOINT ["/game.wasm"]
-COPY /src/dist-web/jnr.wasm /game.wasm
+# JNR Web — static file server for the Emscripten build
+#
+# Prerequisites:
+#   make web          (produces dist-web/)
+#
+# Build:
+#   podman build -t jnr-web .
+#   docker build -t jnr-web .
+#
+# Run locally:
+#   podman run --rm -p 8080:80 jnr-web
+#   Then visit http://localhost:8080
+#
+# Deploy to k3s:
+#   podman save jnr-web | sudo k3s ctr images import -
+#   sudo k3s kubectl apply -f k8s/
+
+FROM docker.io/joseluisq/static-web-server:2
+
+COPY dist-web/ /public/