feat: add discourse-cli for Discourse forum integration

A standalone CLI container (following the redmine-cli pattern) that
lets AI agents and humans read, post, reply, search, and discuss on a
Discourse forum via the REST API. Uses three environment variables
(DISCOURSE_URL, DISCOURSE_API_KEY, DISCOURSE_API_USERNAME) for auth.

Commands: whoami, categories, cat-info, topics/ls, show, create, reply,
update, delete, search, notifications.

Fully validated end-to-end (10/10 checks) against a live Discourse
instance: credential auth, whoami, categories, topics, show, search,
and full write cycle (create + reply + update + delete).

Includes validate.sh for repeatable end-to-end testing using
containerized curl + the CLI image.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

discourse-cli/Dockerfile

@@ -0,0 +1,16 @@
+FROM python:3.12-slim
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    PIP_NO_CACHE_DIR=1
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install -r requirements.txt
+
+COPY src/discourse_cli.py /usr/local/bin/discourse-cli
+RUN chmod +x /usr/local/bin/discourse-cli
+
+ENTRYPOINT ["discourse-cli"]
+CMD ["--help"]