server: Replace hand-rolled IRC with irc (jaraco) library

Switch the IRC server implementation from the custom socket-based parser
to the irc Python library (SingleServerIRCBot), gaining automatic
exponential-backoff reconnection, built-in PING/PONG handling, and
nick-collision recovery for free.

- Add IRCLib server (server/IRCLib.py) extending ThreadedServer:
  _IRCBotAdapter wraps SingleServerIRCBot with a threading.Event stop
  flag so shutdown is clean and on_disconnect skips reconnect when
  stopping. subparse() is implemented directly for alias/grep/rnd/cat.
- Add IRCLib printer (message/printer/IRCLib.py) calling
  connection.privmsg() directly instead of building raw PRIVMSG strings.
- Update factory to use IRCLib for irc:// and ircs://; SSL is now
  passed as a connect_factory kwarg rather than post-hoc socket wrapping.
- Add irc to requirements.txt.

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

Dockerfile

@@ -3,8 +3,8 @@ FROM python:3.11-alpine
 WORKDIR /usr/src/app
 
 COPY requirements.txt /usr/src/app/
-RUN apk add --no-cache bash build-base capstone-dev mandoc-doc man-db w3m youtube-dl aspell aspell-fr py3-matrix-nio && \
-    pip install --no-cache-dir --ignore-installed -r requirements.txt && \
+RUN apk add --no-cache bash build-base capstone-dev mandoc-doc man-db w3m youtube-dl aspell aspell-fr && \
+    pip install --no-cache-dir -r requirements.txt && \
     pip install bs4 capstone dnspython openai && \
     apk del build-base capstone-dev && \
     ln -s /var/lib/nemubot/home /home/nemubot

requirements.txt

@@ -1,2 +1,2 @@
 irc
-matrix-nio
+matrix-nio[e2e]