fix(docker): serve .mjs modules as javascript

.github/workflows/ci-jobs.yml

@@ -98,6 +98,14 @@ jobs:
             sleep 2
           done
           echo "container did not become healthy"; docker logs lobstr; exit 1
+      - name: Verify .mjs is served as JavaScript
+        run: |
+          ct=$(curl -fsSI http://localhost:8080/vendor/secp256k1.mjs | tr -d '\r' | awk -F': ' 'tolower($1)=="content-type"{print $2}')
+          echo "vendor/secp256k1.mjs Content-Type: $ct"
+          case "$ct" in
+            *javascript*) echo "ok" ;;
+            *) echo "ERROR: .mjs not served as JavaScript (browsers will refuse the ES module)"; exit 1 ;;
+          esac
       - name: Stop container
         if: always()
         run: docker rm -f lobstr || true

Dockerfile

@@ -1,3 +1,7 @@
 FROM nginx:alpine
+# nginx's default mime.types has no entry for .mjs, so ES module files would be
+# served as application/octet-stream and browsers refuse to execute them. Register
+# .mjs as JavaScript alongside .js.
+RUN sed -i 's#application/javascript\([[:space:]]\+\)js;#application/javascript\1js mjs;#' /etc/nginx/mime.types
 COPY swa/ /usr/share/nginx/html/
 EXPOSE 80