ui: reword the docs that still spoke of the list drag; keep disabled signals' badge order; stamp the signal generation before the snapshot

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

README.md

@@ -2931,11 +2931,10 @@ now — they are listed so they are not mistaken for anything else:
   controls** are pages of the slide-over, reached from the badge bar. Both panes also have a **locked** mode, which is what a returning user gets: the
   trigger pane shows one line saying what it is set to, the signal list shows only the signals that are
   on, and neither offers a control that changes the configuration -- each heading has an `[edit]` button
-  to switch to the full pane, and back. Dragging a signal onto a plot still works while locked -- filling
-  plots is what the list is for, not configuration -- and a locked row can be dragged from anywhere on it,
-  the colour chip included. In a window too narrow to show both, where the dock is *overlaid on* the
-  plot, the dock steps aside for the length of the drag so there is something under the pointer to drop
-  onto. A **first run** (no session file for that source) comes up
+  to switch to the full pane, and back. Dragging a signal's badge onto a plot still works while locked --
+  filling plots is not configuration. A signal's badge is dragged onto a plot, or onto another badge to
+  reorder the badges (the order is kept for the session only); the slide-over closes for the length of the
+  drag so there is something under the pointer to drop onto. A **first run** (no session file for that source) comes up
   unlocked, because configuring the host is what a first run is for. Each pane's heading also carries its **own switch**, the same control as the
   header bar's button -- clicking either moves both -- because a pane that is *disabled* while its
   feature is off is a pane whose controls you would otherwise have to leave to turn it back on. With the math