fix: Grafana dashboard 'no data' — datasource + Flux queries

- Fix datasource: bucket=smartcity, token=my-super-token, org=digitribe
- Fix dashboard queries: filter by topic tag instead of _measurement
  (all data in measurement 'mqtt_consumer', type in tag 'topic')
- Fix field names: temperature_c→temperature_celsius, luminosity→brightness_lux
- Update dashboard to v3 with 15 panels (airquality, traffic, parking, weather, noise, light)
- Update TODO.md and session_resume

Tested: PM2.5 ✅, Temperature ✅, Vehicle Count ✅ via Grafana API

grafana-datasources.yml

@@ -2,13 +2,18 @@
 apiVersion: 1
 
 datasources:
-  - name: InfluxDB
+  - name: influxdb-smartcity
     type: influxdb
     access: proxy
-    url: http://docker-influxdb-1:8086
-    database: iot_data
-    user: admin
-    password: digitribe972
+    url: http://smart-city-influxdb:8086
+    database: smartcity
+    jsonData:
+      version: Flux
+      organization: digitribe
+      defaultBucket: smartcity
+      tlsSkipVerify: true
+    secureJsonData:
+      token: my-super-token
     isDefault: true
     readOnly: false