Set HOST env var so emdash/astro binds to 0.0.0.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -22,6 +22,7 @@ FROM deps AS runner
 WORKDIR /app
 
 ENV NODE_ENV=production
+ENV HOST=0.0.0.0
 
 RUN adduser --system --uid 1001 astro
 USER astro
@@ -31,4 +32,4 @@ COPY --from=builder /app/dist ./dist
 
 EXPOSE 4321
 
-CMD ["node", "./dist/server/entry.mjs", "--host", "0.0.0.0"]
+CMD ["node", "./dist/server/entry.mjs"]