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>

README.md

@@ -132,7 +132,7 @@ divider's `+` for a new math channel; when every signal is acquired a dim "every
 stands in for the list. While the bar has overflowed into the "N signals" badge the page lists the acquired
 signals too, since their rows are then the only way to each signal's page. There is no signal lock: a
 signal's page and the list always allow acquire, colour, calibration, the math editor and delete.
-A signal badge opens that signal's own page in the slide-over -- colour, the gain and offset (two aligned numbers, a pencil beside each editing just that one) and the *Plot on N*
+A signal badge opens that signal's own page in the slide-over -- the unit, gain and offset and the CONFIG's details directly under the name (aligned rows; a pencil beside the unit, gain and offset edits just that one -- a unit rename is stored per signal name, saved as `[[unit]]` and re-applied to every CONFIG), the colour and the *Plot on N*
 buttons -- and is also the drag handle: drag it onto a plot to draw the signal there, or onto another
 badge to reorder them. Past **six** signal badges the bar shows a single **"N signals"** badge in their
 place (it opens the list, and `+` is hidden): the E-1608's 8 analog inputs and counter would not fit