refactor: rebrand compose, env and docs to BookmarkManager

docs/design-system.md

@@ -1,6 +1,6 @@
-# Cinder — mangaBookmark design system
+# Cinder — BookmarkManager design system
 
-Source of truth: the Claude Design project **mangaBookmark Web UI**
+Source of truth: the Claude Design project **BookmarkManager Web UI**
 (`969ac210-fe02-4c01-ae1b-9a271dcc779a`, `index.html` + siblings
 `archived.html`/`fav.html`/`finished.html`/`new.html`/`login.html`/`mobile.html`,
 `style.css`, `filter.js`). This file records the rules that got implemented so
@@ -118,7 +118,7 @@ root is at the mercy of the host site's CSP.
 Recurring specs (copy these rather than inventing sizes):
 
 - Brand: `400 26px/1 display` (`30px` ≥720px), inline SVG mark (§4) + `<em>` in
-  ember italic — `manga<em>Bookmark</em>`.
+  ember italic — `Bookmark<em>Manager</em>`.
 - Row title: `400 21px/1.2 display` (`22px` ≥720px).
 - Tab: `400 17px display` (`18px` ≥720px), active gets `border-bottom: 2px` in
   `--paper` (`--ember` for Updated) plus `margin-bottom: -1px` so it lands on