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>

decnet/services/conpot.py

@@ -0,0 +1,26 @@
+from decnet.services.base import BaseService
+
+
+class ConpotService(BaseService):
+    """ICS/SCADA honeypot covering Modbus (502), SNMP (161 UDP), and HTTP (80).
+
+    Uses the official honeynet/conpot image which ships a default ICS profile
+    that emulates a Siemens S7-200 PLC.
+    """
+
+    name = "conpot"
+    ports = [502, 161, 80]
+    default_image = "honeynet/conpot"
+
+    def compose_fragment(self, decky_name: str, log_target: str | None = None) -> dict:
+        return {
+            "image": "honeynet/conpot",
+            "container_name": f"{decky_name}-conpot",
+            "restart": "unless-stopped",
+            "environment": {
+                "CONPOT_TEMPLATE": "default",
+            },
+        }
+
+    def dockerfile_context(self):
+        return None