feat(index): preload 37 disabled theme <link> tags for renderer toggle

Preload one disabled <link id="theme-<id>"> per registered theme
between the structural CSS block and the KaTeX link. The renderer
will toggle the disabled attribute on the active link when the theme
changes. The 12 new-theme CSS files (catppuccin-*, one-light,
tokyo-night-storm, synthwave-84, outrun, winter-is-coming-*, solarized-dark-hc,
spring-light) are created in the next task; until then those 12 links
are inert (disabled) and 404 is harmless.

Amit Haridas

src/index.html

@@ -35,6 +35,111 @@
     <link rel="stylesheet" href="styles-welcome.css" />
     <link rel="stylesheet" href="styles-zen.css" />
     <link rel="stylesheet" href="../node_modules/highlight.js/styles/default.css" />
+    <!-- Editor theme CSS — one file per theme, all preloaded as disabled links.
+         src/renderer.js toggles `disabled` on the active one when the theme
+         changes. Source of truth: src/main/ThemeRegistry.bootstrap.js. -->
+    <link id="theme-atomonelight" rel="stylesheet" href="styles/themes/atomonelight.css" disabled />
+    <link id="theme-github" rel="stylesheet" href="styles/themes/github.css" disabled />
+    <link id="theme-light" rel="stylesheet" href="styles/themes/light.css" disabled />
+    <link id="theme-solarized" rel="stylesheet" href="styles/themes/solarized.css" disabled />
+    <link
+      id="theme-gruvbox-light"
+      rel="stylesheet"
+      href="styles/themes/gruvbox-light.css"
+      disabled
+    />
+    <link id="theme-ayu-light" rel="stylesheet" href="styles/themes/ayu-light.css" disabled />
+    <link id="theme-sepia" rel="stylesheet" href="styles/themes/sepia.css" disabled />
+    <link id="theme-paper" rel="stylesheet" href="styles/themes/paper.css" disabled />
+    <link
+      id="theme-rosepine-dawn"
+      rel="stylesheet"
+      href="styles/themes/rosepine-dawn.css"
+      disabled
+    />
+    <link
+      id="theme-concrete-light"
+      rel="stylesheet"
+      href="styles/themes/concrete-light.css"
+      disabled
+    />
+    <link id="theme-dark" rel="stylesheet" href="styles/themes/dark.css" disabled />
+    <link id="theme-onedark" rel="stylesheet" href="styles/themes/onedark.css" disabled />
+    <link id="theme-dracula" rel="stylesheet" href="styles/themes/dracula.css" disabled />
+    <link id="theme-nord" rel="stylesheet" href="styles/themes/nord.css" disabled />
+    <link id="theme-monokai" rel="stylesheet" href="styles/themes/monokai.css" disabled />
+    <link id="theme-material" rel="stylesheet" href="styles/themes/material.css" disabled />
+    <link id="theme-gruvbox-dark" rel="stylesheet" href="styles/themes/gruvbox-dark.css" disabled />
+    <link id="theme-tokyonight" rel="stylesheet" href="styles/themes/tokyonight.css" disabled />
+    <link id="theme-palenight" rel="stylesheet" href="styles/themes/palenight.css" disabled />
+    <link id="theme-ayu-dark" rel="stylesheet" href="styles/themes/ayu-dark.css" disabled />
+    <link id="theme-ayu-mirage" rel="stylesheet" href="styles/themes/ayu-mirage.css" disabled />
+    <link id="theme-oceanic-next" rel="stylesheet" href="styles/themes/oceanic-next.css" disabled />
+    <link id="theme-cobalt2" rel="stylesheet" href="styles/themes/cobalt2.css" disabled />
+    <link
+      id="theme-concrete-dark"
+      rel="stylesheet"
+      href="styles/themes/concrete-dark.css"
+      disabled
+    />
+    <link
+      id="theme-concrete-warm"
+      rel="stylesheet"
+      href="styles/themes/concrete-warm.css"
+      disabled
+    />
+    <link
+      id="theme-catppuccin-latte"
+      rel="stylesheet"
+      href="styles/themes/catppuccin-latte.css"
+      disabled
+    />
+    <link
+      id="theme-catppuccin-frappe"
+      rel="stylesheet"
+      href="styles/themes/catppuccin-frappe.css"
+      disabled
+    />
+    <link
+      id="theme-catppuccin-macchiato"
+      rel="stylesheet"
+      href="styles/themes/catppuccin-macchiato.css"
+      disabled
+    />
+    <link
+      id="theme-catppuccin-mocha"
+      rel="stylesheet"
+      href="styles/themes/catppuccin-mocha.css"
+      disabled
+    />
+    <link id="theme-one-light" rel="stylesheet" href="styles/themes/one-light.css" disabled />
+    <link
+      id="theme-tokyo-night-storm"
+      rel="stylesheet"
+      href="styles/themes/tokyo-night-storm.css"
+      disabled
+    />
+    <link id="theme-synthwave-84" rel="stylesheet" href="styles/themes/synthwave-84.css" disabled />
+    <link id="theme-outrun" rel="stylesheet" href="styles/themes/outrun.css" disabled />
+    <link
+      id="theme-winter-is-coming-light"
+      rel="stylesheet"
+      href="styles/themes/winter-is-coming-light.css"
+      disabled
+    />
+    <link
+      id="theme-winter-is-coming-dark"
+      rel="stylesheet"
+      href="styles/themes/winter-is-coming-dark.css"
+      disabled
+    />
+    <link
+      id="theme-solarized-dark-hc"
+      rel="stylesheet"
+      href="styles/themes/solarized-dark-hc.css"
+      disabled
+    />
+    <link id="theme-spring-light" rel="stylesheet" href="styles/themes/spring-light.css" disabled />
     <!-- KaTeX math rendering — bundled locally (fonts included) for offline use -->
     <link rel="stylesheet" href="../assets/katex/katex.min.css" />
   </head>