fix standalone web health binding

deploy/railway-web.Dockerfile

@@ -36,5 +36,6 @@ ARG NEXT_PUBLIC_SUPABASE_URL
 ARG NEXT_PUBLIC_SUPABASE_ANON_KEY
 ENV NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL} \
     NEXT_PUBLIC_SUPABASE_ANON_KEY=${NEXT_PUBLIC_SUPABASE_ANON_KEY}
-ENV NODE_ENV=production
+ENV NODE_ENV=production \
+    HOSTNAME=0.0.0.0
 CMD ["node", "server.js"]

frontend/tests/staging-backend-workflows.test.ts

@@ -144,6 +144,7 @@ test("railway web image uses Next standalone runtime output", () => {
   );
   assert.doesNotMatch(dockerfile, /COPY --from=build \/app \/app/);
   assert.match(dockerfile, /WORKDIR \/app\/frontend/);
+  assert.match(dockerfile, /ENV NODE_ENV=production \\\n    HOSTNAME=0\.0\.0\.0/);
   assert.match(dockerfile, /CMD \["node", "server\.js"\]/);
   assert.doesNotMatch(dockerfile, /npm start/);
 });