Add Tasmota timezone handling and dashboard updates

docs/ARCHITECTURE.md

@@ -140,7 +140,7 @@ timestamp: payload Time or message receive time
 
 - prefer payload `Time` when present
 - accept RFC3339 and timezone-less Tasmota timestamps in the form `2006-01-02T15:04:05`
-- current implementation interprets timezone-less timestamps as UTC
+- interpret timezone-less timestamps in the configured `tasmota_time_zone` location and convert them to UTC for storage
 
 ## Failure handling