fix(packaging): move templates/ into decnet/ package so they ship with pip install

The docker build contexts and syslog_bridge.py lived at repo root, which
meant setuptools (include = ["decnet*"]) never shipped them. Agents
installed via `pip install $RELEASE_DIR` got site-packages/decnet/** but no
templates/, so every deploy blew up in deployer._sync_logging_helper with
FileNotFoundError on templates/syslog_bridge.py.

Move templates/ -> decnet/templates/ and declare it as setuptools
package-data. Path resolutions in services/*.py and engine/deployer.py drop
one .parent since templates now lives beside the code. Test fixtures,
bandit exclude path, and coverage omit glob updated to match.

decnet/templates/telnet/Dockerfile

@@ -0,0 +1,51 @@
+ARG BASE_IMAGE=debian:bookworm-slim
+FROM ${BASE_IMAGE}
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    busybox-static \
+    rsyslog \
+    procps \
+    net-tools \
+    && rm -rf /var/lib/apt/lists/*
+
+# rsyslog: forward auth.* and user.* to named pipe in RFC 5424 format
+RUN printf '%s\n' \
+    '# syslog-relay log bridge — auth + user events → named pipe as RFC 5424' \
+    '$template RFC5424fmt,"<%PRI%>1 %TIMESTAMP:::date-rfc3339% %HOSTNAME% %APP-NAME% %PROCID% %MSGID% %STRUCTURED-DATA% %msg%\n"' \
+    'auth,authpriv.*  |/run/systemd/journal/syslog-relay;RFC5424fmt' \
+    'user.*           |/run/systemd/journal/syslog-relay;RFC5424fmt' \
+    > /etc/rsyslog.d/50-journal-forward.conf
+
+# Disable imklog — containers can't read /proc/kmsg
+RUN sed -i 's/^\(module(load="imklog"\)/# \1/' /etc/rsyslog.conf
+
+# Silence default catch-all rules
+RUN sed -i \
+    -e 's|^\(\*\.\*;auth,authpriv\.none\)|#\1|' \
+    -e 's|^auth,authpriv\.\*|#auth,authpriv.*|' \
+    /etc/rsyslog.conf
+
+# Realistic motd and issue banner
+RUN echo "Ubuntu 20.04.6 LTS" > /etc/issue.net && \
+    echo "Welcome to Ubuntu 20.04.6 LTS (GNU/Linux 5.4.0-150-generic x86_64)" > /etc/motd && \
+    echo "" >> /etc/motd && \
+    echo " * Documentation:  https://help.ubuntu.com" >> /etc/motd
+
+# Fake lived-in files
+RUN mkdir -p /root/scripts /root/backups && \
+    printf '#!/bin/bash\n# DB backup script\nmysqldump -u root -padmin prod_db > /root/backups/db.sql\n' > /root/scripts/backup.sh && \
+    printf 'DB_HOST=10.0.0.5\nDB_USER=admin\nDB_PASS=changeme123\n' > /root/.env && \
+    printf 'alias ll="ls -alF"\nalias la="ls -A"\nexport HISTSIZE=1000\n' >> /root/.bashrc
+
+# Log bash commands via syslog
+RUN echo 'PROMPT_COMMAND='"'"'logger -p user.info -t bash "CMD uid=$UID pwd=$PWD cmd=$(history 1 | sed "s/^ *[0-9]* *//")";'"'" >> /root/.bashrc
+
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+EXPOSE 23
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD kill -0 1 || exit 1
+
+ENTRYPOINT ["/entrypoint.sh"]