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/invariants-plot-and-layout.md

@@ -110,7 +110,9 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   does not propagate its child's height), and content that is taller than the plot -- the trigger form
   on a 470 px window -- scrolls inside the panel instead of growing it. The widgets that go in a page
   are reparented into it; their widths must fit 360 minus the border (the trigger form measures 267
-  minimum, the E-1608's panels 197).
+  minimum, the E-1608's panels 197). **One page wider than that widens the panel
+  for all of them** (the stack measures every page): the signals page's hint line once did, unwrapped, and
+  `[slideover] panel=` read 376 instead of 360; the label now wraps.
 - **The badge bar has a fixed height and sits outside the overlay.** `badge_bar` is 36 px
   (`height-request`) between `plot_overlay` and the status line, so the plot above it never moves when a
   badge's text changes (`bar_h` = `bar_h_after` in `[badges]`). This is "layout must not depend on
@@ -119,8 +121,17 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   spare on the right) and never its height. The badge labels are not ellipsized: a name long enough to
   need it would be a defect of the kind's `display_name()`. Rows that appear by trigger condition appear
   inside the slide-over's scroller, never in the bar.
+- **The signal badges live in a scroller, so the bar's minimum width never depends on the signal count.**
+  The bar's signals slot holds a `GtkScrolledWindow` (horizontal `EXTERNAL`, vertical `NEVER`) around one
+  row of badges and the `+`, because a button row's minimum width is the sum of its children: nine badges
+  (the E-1608: eight inputs and the counter) would push the window's minimum width past a laptop screen.
+  Past `kMaxSignalBadges` (6) the row is replaced by one "N signals" badge, which also stands for the `+`.
+  The bar's height stays 36 px in every one of these states (`bar_h_fixed` in `[sigbadges]`), and
+  `bar_min_w` reads the same with one signal, nine signals and the overflow (329 on the E-1608, 336 on UDPS:
+  the Source badge of each kind reads differently). A change that makes it grow with the signal count has
+  taken the scroller out of the measurement.
 - **The dock's width is fixed too** (`side_column` `width-request` 300, the split view's 320 px floor
-  and cap), and it holds one scroller with the signal list, the cursors and the measurements. A
+  and cap), and it holds one scroller with the cursors and the measurements. A
   section's visibility is never what makes the dock taller; the scroller is what absorbs the extra.
 - **Trace slots are identified by signal name, not channel index.** Enabling a signal
   or a new CONFIG renumbers the channel list, so an index would silently re-point a