feat: add Theme API v2 with token compiler, skin slot

lib/plugin-storage.ts

@@ -1,9 +1,11 @@
 // IndexedDB storage for plugin/theme binary blobs (JS bundles, CSS, previews)
 
 const DB_NAME = 'bulwark-plugins';
-const DB_VERSION = 1;
+// Bumped to 2 to add the theme-skin store; existing stores are preserved.
+const DB_VERSION = 2;
 const STORE_PLUGINS = 'plugin-code';
 const STORE_THEMES = 'theme-css';
+const STORE_THEME_SKINS = 'theme-skin';
 const STORE_PREVIEWS = 'previews';
 
 function openDB(): Promise<IDBDatabase> {
@@ -18,6 +20,9 @@ function openDB(): Promise<IDBDatabase> {
       if (!db.objectStoreNames.contains(STORE_THEMES)) {
         db.createObjectStore(STORE_THEMES);
       }
+      if (!db.objectStoreNames.contains(STORE_THEME_SKINS)) {
+        db.createObjectStore(STORE_THEME_SKINS);
+      }
       if (!db.objectStoreNames.contains(STORE_PREVIEWS)) {
         db.createObjectStore(STORE_PREVIEWS);
       }
@@ -83,6 +88,18 @@ export const pluginStorage = {
     await deleteItem(STORE_THEMES, themeId);
   },
 
+  // Theme skin CSS — separate store so it can be present/absent independently
+  // of the colour-token CSS (e.g. some v2 themes ship colours only).
+  async saveThemeSkin(themeId: string, skin: string): Promise<void> {
+    await putItem(STORE_THEME_SKINS, themeId, skin);
+  },
+  async getThemeSkin(themeId: string): Promise<string | null> {
+    return getItem<string>(STORE_THEME_SKINS, themeId);
+  },
+  async deleteThemeSkin(themeId: string): Promise<void> {
+    await deleteItem(STORE_THEME_SKINS, themeId);
+  },
+
   // Preview images (stored as data URIs)
   async savePreview(id: string, dataUri: string): Promise<void> {
     await putItem(STORE_PREVIEWS, id, dataUri);