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/smart-city-dashboards.json

@@ -0,0 +1,16 @@
+{
+  "annotations": {"list": []},
+  "editable": true,
+  "fiscalYearStartMonth": 0,
+  "graphTooltip": 0,
+  "links": [],
+  "panels": [],
+  "schemaVersion": 36,
+  "style": "dark",
+  "tags": ["smart-city"],
+  "templating": {"list": []},
+  "time": {"from": "now-24h", "to": "now"},
+  "title": "Smart City Dashboards",
+  "timezone": "Americas/Martinique",
+  "uid": "smart-city-dashboards"
+}