rename(547): the mark is a clasped grimoire

favicon.svg is a violet book with gold corners and clasp and a four-pointed star
in a ring, replacing the indigo book with a spark. It is rendered to 192 and 512
PNG app icons and a 180 touch icon on the page surface.

manifest.json lists those icons instead of a favicon.ico that never existed. It
describes the product as the README does, and takes its colours from the design
system's page surface. index.html's theme-color follows.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/index.html

@@ -4,8 +4,9 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="apple-touch-icon" href="/apple-touch-icon.png">
     <link rel="manifest" href="/manifest.json">
-    <meta name="theme-color" content="#6c63ff">
+    <meta name="theme-color" content="#14171A">
     <meta name="mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">