ui: per-signal slide-over pages; the drop's assignment and the colour reset as shared functions

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

docs/claude/probe-readings.md

@@ -2634,6 +2634,19 @@ loads a file as the previous version wrote it (`side_tab = "measure"`) into a `L
 leave `dock_shown` at the default (`true`), so `ok=1` requires `dock_shown == default` -- the parser ignores unknown keys, and this is what says the old key still does not break a session. A load that
 left the caller's `false` alone would read `dock_shown=0 default=1 ok=0`. The probe writes only to a temp path.
 
+## `[signalpage]`
+
+```
+[signalpage] name=sine open=1 pages=1 enable_visible=1 plot_buttons=1 plot_on_row0=1 removed=1 btn_row0=1 back_to_list=1 row_opens=1 pruned=1 rows=1
+```
+
+`UDPSCOPE_PROBE_SIGNAL_PAGES_MS` builds and drives the page of the first streamed signal. `open=1` (the slide-over shows `signal:<name>`), `pages=1`
+(one page in `App::signal_pages`), `enable_visible=1` (the acquire tick is shown in live mode; `0` in a file view), `plot_buttons=` equal to
+`rows=` (one "Plot on" button per figure row), `plot_on_row0=1` (`assign_signal_to_row()` returned true and the signal is plotted), `removed=1`
+(the page's "Remove from plots" took it off), `btn_row0=1` (the "Plot on 1" button, the user's path, put it back), `back_to_list=1` ("All signals"
+target), `row_opens=1` (activating the list row opens the page), and `pruned=1`: a math channel's page was opened, its **Delete** button clicked, and
+the slide-over closed and the page was dropped by `signal_pages_sync()`. `pruned=-1` means no math channel could be added; `0` is a stale page.
+
 ## `[badges]`
 
 ```