Add 20 honeypot services: email, DB, ICS, cloud, IoT, network protocols

Tier 1 (upstream images): telnet (cowrie), smtp (mailoney),
elasticsearch (elasticpot), conpot (Modbus/S7/SNMP ICS).

Tier 2 (custom asyncio honeypots): pop3, imap, mysql, mssql, redis,
mongodb, postgres, ldap, vnc, docker_api, k8s, sip, mqtt, llmnr, snmp,
tftp — each with Dockerfile, entrypoint, and protocol-accurate
handshake/credential capture.

Adds 256 pytest cases covering registration, compose fragments,
LOG_TARGET propagation, and Dockerfile presence for all 25 services.

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

templates/mqtt/Dockerfile

@@ -0,0 +1,12 @@
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    python3 \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY mqtt_honeypot.py /opt/mqtt_honeypot.py
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+EXPOSE 1883
+ENTRYPOINT ["/entrypoint.sh"]