ui: a signal's details sit directly under its name; its unit is user-changeable and saved with the session

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/USER-GUIDE.md

@@ -65,9 +65,11 @@ the badge bar. Drag the badge onto a plot row to add a trace; drag it again to a
 the same signal twice, or onto another badge to reorder the badges. The colour is per *signal*, so
 the same signal is the same colour wherever it appears.
 
-Clicking a signal's badge opens its own page: the colour, **Plot on** buttons for the rows, and
-**Gain** and **Offset**, shown as two aligned numbers with a pencil button each that edits that one value.
-They are applied at ingest, so the measurements and the export carry the same numbers the plot shows.
+Clicking a signal's badge opens its own page. Directly under the name are its **Unit**, **Gain** and
+**Offset** — each with a pencil button that edits that one value — and then what the stream declared about
+it (type, size, range, sample rate, timing). Below come the colour and the **Plot on** buttons for the
+rows. Gain and offset are applied at ingest, so the measurements and the export carry the same numbers the
+plot shows; a renamed unit is used there too and is saved with the session.
 
 ## 4. The window and navigation