docs: the signal badges, the signal pages and the six-badge overflow (step 2 of the redesign)

Also wrap the signals page's hint line, which at 375 px minimum widened the whole slide-over panel to 376.

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

docs/claude/architecture.md

@@ -99,19 +99,23 @@ touching the data path.
 - **`SlideOver`** (`src/ui_slideover.cpp`) is one `GtkRevealer` holding a `GtkStack`, added as the second
   child placed *over* the plot (after the layout editor's buttons) in `GtkOverlay#plot_overlay`. A page is
   a `slideover_add_page(app, id, title, widget)`: the widget is wrapped in a `GtkScrolledWindow` of its
-  own and registered under its id (`trigger`, `source-<id>`; `signal:<name>`, `signals`, `measure`,
-  `cursors` and `events` are reserved for later steps). One page is open at a time and `App::slideover.page`
+  own and registered under its id (`trigger`, `source-<id>`, `signals` (the signal list) and
+  `signal:<name>` (one signal's page, `src/ui_signal_page.cpp`, created on demand by `signal_page_ensure()`
+  and pruned by `signal_pages_sync()`, which `rebuild_signal_panels()` ends with); `measure`, `cursors`
+  and `events` are reserved for later steps). One page is open at a time and `App::slideover.page`
   is its id, empty when closed. The open page is **not** a session value. Esc, *Close*, a second click on the
   badge and a click on the plot close it; the click-away is a capture-phase observer (see
   [invariants-gtk-and-chrome.md](invariants-gtk-and-chrome.md)). With two or more `source-*` pages, an
   `AdwToggleGroup` under the header is the segmented switch between them.
 - **`BadgeBar`** (`src/ui_badges.cpp`) is the fixed-height row between the plot and the status line
-  (`main-window.ui` `badge_bar`, two slots: signals, left, empty until step 2; system, right, holding the
-  **Trigger** and **Source** badges). A badge is a flat button whose `page` is the slide-over page it
+  (`main-window.ui` `badge_bar`, two slots: signals, left, a scroller holding one badge per enabled signal
+  and the `+`, or a single "N signals" badge past six; system, right, holding the **Trigger** and
+  **Source** badges). `sync_signal_badges()` rebuilds the signal badges (from `rebuild_signal_panels()`);
+  their order is `App::badge_order`, in memory only. A badge is a flat button whose `page` is the slide-over page it
   toggles; the Source badge's page is the first `source-*` page, and a kind with none (UDPS, Flat UDP, a
   file) leaves it a read-out with `can_target` off.
 - **The dock** is the `AdwOverlaySplitView` sidebar (`side_box` > `dock_scroller` > `dock_page`): the
-  signal list, the cursors and the measurements in one scroller. It holds no tab switcher and no
+  cursors and the measurements only, in one scroller (the signal list is the `signals` page). It holds no tab switcher and no
   revealer, and it does not hold a source kind's panels (those are slide-over pages).
 
 **When each is built and when it is read.** `build_slideover()` runs in `on_activate` right after the tour