Add mqtt_subscribe and muc_send skills

- mqtt_subscribe: dynamically subscribe/unsubscribe to any MQTT topic,
  received messages are forwarded to XMPP admins
- muc_send: post a message to the XMPP MUC group (agents@muc.xmpp.ovh)

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

skills/mqtt_subscribe.py

@@ -0,0 +1,59 @@
+"""
+Skill MQTT_SUBSCRIBE — s'abonner dynamiquement à un topic MQTT.
+
+Les messages reçus sont transmis via XMPP (admin) et loggés.
+
+Usage LLM :
+  SKILL:mqtt_subscribe ARGS:subscribe | <topic>
+  SKILL:mqtt_subscribe ARGS:unsubscribe | <topic>
+  SKILL:mqtt_subscribe ARGS:list
+"""
+import logging
+
+DESCRIPTION = "S'abonner / se désabonner dynamiquement d'un topic MQTT et recevoir les messages"
+USAGE = "SKILL:mqtt_subscribe ARGS:subscribe|<topic>  ou  unsubscribe|<topic>  ou  list"
+
+logger = logging.getLogger(__name__)
+
+# Stockage des souscriptions dynamiques : {topic: callback}
+_dynamic_subs: dict = {}
+
+
+def run(args: str, context) -> str:
+    parts = [p.strip() for p in args.split("|", 1)]
+    action = parts[0].lower()
+
+    if action == "list":
+        if not _dynamic_subs:
+            return "Aucun topic MQTT surveillé."
+        return "Topics surveillés :\n" + "\n".join(f"  • {t}" for t in _dynamic_subs)
+
+    if len(parts) < 2 or not parts[1]:
+        return "Format : subscribe|<topic>  ou  unsubscribe|<topic>  ou  list"
+
+    topic = parts[1]
+
+    if action == "unsubscribe":
+        if topic in _dynamic_subs:
+            del _dynamic_subs[topic]
+            return f"Désabonné du topic '{topic}'."
+        return f"Pas abonné à '{topic}'."
+
+    if action == "subscribe":
+        if topic in _dynamic_subs:
+            return f"Déjà abonné à '{topic}'."
+
+        agent_id = context.agent_id
+
+        def _on_message(msg, t):
+            payload = msg.payload if hasattr(msg, "payload") else str(msg)
+            text = f"[MQTT:{t}] {payload}"
+            logger.info(f"[mqtt_subscribe] {text}")
+            if context.xmpp:
+                context.xmpp.send_to_all_admins(text)
+
+        _dynamic_subs[topic] = _on_message
+        context.mqtt.subscribe(topic, _on_message)
+        return f"Abonné au topic '{topic}'. Les messages seront transmis via XMPP."
+
+    return f"Action inconnue '{action}'. Utilise : subscribe, unsubscribe, list."