Batch 2 : file d'attente SQLite + pause/resume + stats par agent

- task_queue.py : module FIFO SQLite (queue.db) pour agent2_debian13 et agent2_ansible
- agent2_debian13.py : intégration queue, topic agents/agent2_debian13/control,
  commandes pause/resume/report, QoS 1 + clean_session=False
- agent2_ansible.py : idem

Les tâches MQTT sont maintenant persistées avant exécution.
Le worker traite en FIFO, les tâches en pause s'accumulent sans être perdues.

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

config/agents_online.json

@@ -0,0 +1,30 @@
+{
+  "agent2_deploy": {
+    "status": "online",
+    "agent": "agent2_deploy",
+    "jid": "agent2_deploy@xmpp.ovh",
+    "mqtt_inbox": "agents/agent2_deploy/inbox",
+    "last_seen": 1772919416.397681
+  },
+  "agent2_ansible": {
+    "status": "online",
+    "agent": "agent2_ansible",
+    "jid": "agent2_ansible@xmpp.ovh",
+    "mqtt_inbox": "agents/agent2_ansible/inbox",
+    "last_seen": 1772919417.011551
+  },
+  "agent2_debian13": {
+    "status": "online",
+    "agent": "agent2_debian13",
+    "jid": "agent2_debian13@xmpp.ovh",
+    "mqtt_inbox": "agents/agent2_debian13/inbox",
+    "last_seen": 1772919416.9976034
+  },
+  "agent2_test": {
+    "status": "online",
+    "agent": "agent2_test",
+    "jid": "agent2_test@xmpp.ovh",
+    "mqtt_inbox": "agents/agent2_test/inbox",
+    "last_seen": 1772919358.6175494
+  }
+}