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>

docker-compose.dev.yaml

@@ -0,0 +1,13 @@
+services:
+  sermo:
+    build: .
+    container_name: sermo-bbs
+    ports:
+      - "2324:2323"
+    volumes:
+      - ./:/app/
+    environment:
+      - BBS_PORT=2323
+    restart: unless-stopped
+    stdin_open: true
+    tty: true