docker: nginx listens on 80 and 8890, backend moves to internal 8891

Deploy platforms that route to the container's exposed/compose port
(8890) were hitting the fun backend directly, which 404s unmatched
GET paths. Now nginx answers on both ports so either routing lands
on the SPA/API proxy layer.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Dockerfile

@@ -25,9 +25,9 @@ COPY docker/nginx.conf /etc/nginx/http.d/default.conf
 COPY docker/entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh && mkdir -p /app/data
 
-ENV CYIBOX_PORT=8890 \
+ENV CYIBOX_PORT=8891 \
     CYIBOX_DB=/app/data/cyibox.db
 
-EXPOSE 80
+EXPOSE 80 8890
 VOLUME ["/app/data"]
 ENTRYPOINT ["/entrypoint.sh"]