Shell 1.13.0: the Layouts menu lists the tiles a layout holds but the board is not showing, with a ✕ to remove each

A tile whose module stopped offering its picker entry — Slack's Send message
and Quick replies since the Send Message module took them over — kept its
place in the layout and drew nothing, as designed, but still held its grid
cells with no control anywhere to let them go: a dead area the operator
could not place anything in.

The Layouts menu now has a Not shown section, present only while the layout
holds such a tile. One row per tile: its title (or the module's name plus
the variant, or the module id when it is not installed), why in a few words
— "not offered right now", "module disabled", "module needs a newer
ProdDash", "module not installed" — and a drawn ✕ with a tooltip that
removes it, saves the layout and frees the cells, leaving the menu open as
the Grid Size stepper and Alerts do. The section repaints while the menu is
open whenever tiles become offered or stop being, and only when the list
changed. A tile that merely waits for its module keeps its place as before.

GET /api/modules also returns `inactive` — the installed modules that are
not running, id, name and reason only — so a dashboard can tell a disabled
module from one that is not installed. The toast after loading a named
layout now says the Layouts menu can remove the tiles it did not show.
README and the module guide updated.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/MODULE-GUIDE.md

@@ -688,8 +688,11 @@ module.exports = {
   tile added from an entry only when that entry (or one of its `aliases`) is
   in your list right now; otherwise the tile keeps its place in the layout,
   draws nothing, and appears the moment your list offers it again — a
-  Service timer waits for PCO Plan, a transcript for its channel. So your
-  client is never asked to render an entry you did not offer at mount time.
+  Service timer waits for PCO Plan, a transcript for its channel. The
+  operator can remove such a tile from the Layouts menu's **Not shown**
+  section, so an entry you retire for good (a send box that moved to another
+  module) leaves no dead cells behind. So your client is never asked to
+  render an entry you did not offer at mount time.
   One case is still yours: an entry that vanishes *after* the tile mounted
   (a timer deleted in ProPresenter mid-service). Render nothing for it — no
   placeholder, no error — and the shell folds the tile away at its next
@@ -1044,7 +1047,8 @@ client-side failures (a tile that fails to start says so in the tile).
 
 **Poke the pieces directly:**
 
-- `GET /api/modules` — what the shell sees (your manifest + non-secret config).
+- `GET /api/modules` — what the shell sees (your manifest + non-secret
+  config; `inactive` names the installed modules that are not running).
 - `GET /api/modules/<id>/...` — your routes, `curl`-able. For SSE:
   `curl -N http://localhost:24500/api/modules/<id>/stream`.
 - `GET /api/admin/state` — enabled flags, health, mount errors.