🚧 Add topic explorer

specification.md

@@ -1174,6 +1174,23 @@ set retained flag
 inspect MQTT 5 properties
 ```
 
+## 35.1 Consolidated topic view
+
+The live message view shall be organized as ONE ROW PER KNOWN TOPIC
+(rather than one row per received message), so an active topic tree is
+browsable at a glance. For each row:
+
+* on receiving a new message, the row shall HIGHLIGHT THE DIFFERENCES
+  between the new message and the previously known message for that
+  topic (payload, QoS, retain flag and MQTT 5 properties that changed)
+* the row shall GLOW briefly when a new message arrives, so the user
+  notices activity without watching every row
+
+The full KNOWN HISTORY of each topic shall be browsable: selecting a
+topic row opens its message history (most recent first), from which any
+entry can be inspected in detail (payload as text/hex, QoS, retain
+flag, MQTT 5 properties, arrival time).
+
 Example:
 
 ```text