Sunred Smart Triangle heater: naming tweaks

- use capitalised first word for entity and device names per HA convention
- use model and model_id rather than name and model for model info

PR #2837

custom_components/tuya_local/devices/sunred_smart_triangle_heater.yaml

@@ -1,9 +1,9 @@
-name: heater
+name: Heater
 products:
   - id: f2sycol9awtabrsp
     manufacturer: Sunred
-    model: ZHQ2582
-    name: SMART Triangle Dark Wall Model
+    model_id: ZHQ2582
+    model: Smart Triangle Dark Wall
 entities:
   - entity: switch
     dps:
@@ -18,7 +18,6 @@ entities:
         type: integer
         unit: C
         class: measurement
-        readonly: true
   - entity: number
     category: config
     name: Level