feat: migrate InfluxDB and Grafana from digital-twin/ to smart-city/ stack

- docker-compose.influxdb.yml: InfluxDB v2 on smartcity-shared + traefik-public
- docker-compose.grafana.yml: Grafana 10.2 on smartcity-shared + traefik-public
- grafana/provisioning/: dashboards + datasources updated for smart-city
- pulsar/docker-compose.yml: added smartcity-shared network for simulator access

Services migrated (preserving existing volumes):
  - digital-twin-influxdb → smart-city-influxdb
  - digital-twin-grafana  → smart-city-grafana

Traefik routes updated:
  - influxdb.digitribe.fr → smart-city-influxdb:8086
  - grafana.digitribe.fr  → smart-city-grafana:3000

grafana/provisioning/dashboards/twin-overview.json

@@ -0,0 +1,84 @@
+{
+  "timezone": "Americas/Martinique",
+  "timepicker": {
+    "time_options": [
+      "5m",
+      "15m",
+      "1h",
+      "6h",
+      "12h",
+      "24h",
+      "2d"
+    ]
+  },
+  "title": "TWIN Supply Chain - Overview",
+  "tags": [
+    "twin",
+    "supply-chain"
+  ],
+  "panels": [
+    {
+      "id": 1,
+      "title": "Active Shipments",
+      "type": "stat",
+      "gridPos": {
+        "x": 0,
+        "y": 0,
+        "w": 6,
+        "h": 4
+      },
+      "targets": [
+        {
+          "query": "from(bucket: \"iot_data\") |> range(start: -1h) |> filter(fn: (r) => r[\"_measurement\"] == \"shipment\") |> count()"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "short"
+        }
+      }
+    },
+    {
+      "id": 2,
+      "title": "Inventory Level",
+      "type": "stat",
+      "gridPos": {
+        "x": 6,
+        "y": 0,
+        "w": 6,
+        "h": 4
+      },
+      "targets": [
+        {
+          "query": "from(bucket: \"iot_data\") |> range(start: -1h) |> filter(fn: (r) => r[\"_measurement\"] == \"inventory\") |> mean()"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "short"
+        }
+      }
+    },
+    {
+      "id": 3,
+      "title": "Pending Orders",
+      "type": "stat",
+      "gridPos": {
+        "x": 12,
+        "y": 0,
+        "w": 6,
+        "h": 4
+      },
+      "targets": [
+        {
+          "query": "from(bucket: \"iot_data\") |> range(start: -1h) |> filter(fn: (r) => r[\"_measurement\"] == \"order\") |> count()"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "short"
+        }
+      }
+    }
+  ]
+}