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/datasources/datasources.yml

@@ -0,0 +1,51 @@
+# Grafana datasources - Smart City Digital Twin Martinique
+# Each datasource is editable and uses the container DNS name in smartcity-shared network
+apiVersion: 1
+
+datasources:
+  # ── InfluxDB v2 (time-series IoT data) ──────────────────────────────────────
+  - name: InfluxDB-v2
+    type: influxdb
+    access: proxy
+    url: http://smart-city-influxdb:8086
+    isDefault: true
+    editable: true
+    jsonData:
+      version: Flux
+      organization: digitribe
+      defaultBucket: iot_data
+    secureJsonData:
+      token: my-super-secret-admin-token
+
+  # ── FIWARE Orion-LD (NGSI-LD context broker) ────────────────────────────────
+  # Requires grafana-simple-json-datasource plugin
+  - name: FIWARE Orion
+    type: grafana-simple-json-datasource
+    access: proxy
+    url: http://fiware-gis-quickstart-orion-1:1026
+    editable: true
+    jsonData:
+      queryURLTemplate: "/ngsi-ld/v1/entities?type={{type}}"
+      method: GET
+
+  # ── GeoServer WMS (spatial data) ────────────────────────────────────────────
+  # GeoServer is an external service reachable via its container name
+  - name: GeoServer WMS
+    type: grafana-simple-json-datasource
+    access: proxy
+    url: http://docker-geoserver-1:8080/geoserver
+    editable: true
+    jsonData:
+      queryURLTemplate: "/geoserver/wfs?service=WFS&version=2.0&request=GetFeature&typeName={{type}}"
+      method: GET
+
+  # ── FROST-Server (SensorThings API) ──────────────────────────────────────────
+  # Requires grafana-simple-json-datasource plugin
+  - name: FROST-Server
+    type: grafana-simple-json-datasource
+    access: proxy
+    url: http://frost-api-8090:8090/FROST-Server/v1.1
+    editable: true
+    jsonData:
+      queryURLTemplate: "/Things?$top=1"
+      method: GET