Initial SERMO-BBS: a telnet PC that boots SERMO-DOS

A rubbs-based telnet server that drops every caller into a simulated PC:
it POSTs, boots, loads SERMO-DOS, and lands at a C:\> prompt. Built-in DOS
commands (VER/DATE/TIME/ECHO/MEM/DIR/CLS/HELP/EXIT) behave; anything else
is routed to Sermo::Oracle as a question — the hook for a future LLM.

Built on rubbs' configurable BBS::FakeOS engine; the whole OS lives in
lib/sermo/dos.rb as a FakeOS.define block, so new character-mode OSes are
added as config files, not engine changes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,17 @@
+FROM ruby:3.3-alpine
+
+RUN apk add --no-cache git build-base
+
+WORKDIR /app
+
+COPY Gemfile Gemfile.lock ./
+RUN bundle install
+
+COPY sermo.rb entrypoint.sh ./
+COPY lib/ ./lib/
+
+RUN chmod +x entrypoint.sh
+
+EXPOSE 2323
+
+ENTRYPOINT ["./entrypoint.sh"]