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-gtk-and-chrome.md

@@ -225,7 +225,7 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   take room has to be hidden and not merely unrevealed; the revealer keeps the slide while the pane
   *is* open. The allocated width is how this was found -- the revealer's own measure said 0.
   **The sidebar is one dock now, and has no `GtkRevealer` left in it**: a single `GtkScrolledWindow`
-  (`dock_scroller`) holding the signal list, the cursors and the measurements one under another. It
+  (`dock_scroller`) holding the cursors and the measurements one under another. It
   replaced an `AdwViewSwitcher` over an `AdwViewStack`, whose four text tabs did not fit 320 px (and a source
   can add more); a source kind's own panels are slide-over pages, not dock sections. The reason is the one
   this trap teaches: sections competing for one 320 px column each left every one of them short of room, and