Add entrypoint.sh that updates rubbs before starting

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

Dockerfile

@@ -7,11 +7,11 @@ WORKDIR /app
 COPY Gemfile Gemfile.lock ./
 RUN bundle install
 
-COPY bbs.rb ./
+COPY bbs.rb entrypoint.sh ./
 COPY lib/ ./lib/
 
-RUN mkdir -p /app/data
+RUN mkdir -p /app/data && chmod +x entrypoint.sh
 
 EXPOSE 2323
 
-CMD ["bundle", "exec", "ruby", "bbs.rb"]
+ENTRYPOINT ["./entrypoint.sh"]