Fix: Grafana dashboard Orion-LD + Stellio persistence investigation

- ✅ Grafana dashboard updated with proper time filters
- ✅ Orion-LD pipeline validated (6 tables, 5+ rows in CrateDB)
- ❌ Stellio pipeline blocked: QuantumLeap /v2/notify doesn't support NGSI-LD native format (TypeError: argument of type 'float' is not iterable)
- 📝 QuantumLeap expects NGSI-v2 format ({"value": X, "type": "Number"}) but receives NGSI-LD (direct values)

Next steps:
- Focus on Orion-LD pipeline (working)
- Consider Stellio as experimental / future work

grafana-simple.json

@@ -0,0 +1,26 @@
+{
+  "dashboard": {
+    "id": null,
+    "uid": "orion-ld-simple",
+    "title": "Smart City - Orion-LD Simple",
+    "tags": ["smart-city", "orion-ld"],
+    "timezone": "browser",
+    "panels": [
+      {
+        "id": 1,
+        "type": "timeseries",
+        "title": "Température",
+        "datasource": {"type": "postgres", "uid": "d43222c0-ad4e-4c49-9759-f822211e669e"},
+        "targets": [
+          {
+            "refId": "A",
+            "datasource": {"type": "postgres", "uid": "d43222c0-ad4e-4c49-9759-f822211e669e"},
+            "rawQuery": true,
+            "rawSql": "SELECT time_index as \"time\", AVG(temperature) as \"temp\" FROM quantumleap.etairqualityobserved WHERE $__timeFilter(time_index) GROUP BY time_index ORDER BY time_index"
+          }
+        ]
+      }
+    ]
+  },
+  "overwrite": false
+}