chore: media compression feature groundwork

docs/design/components.md

@@ -849,3 +849,7 @@ Source: `source/activity-spec.js` (component inventory) and `source/ActivityFram
 - Day separators are full-width rows of the table. The "When" cell carries the exact time as its `title`.
 - The sentence is composed from the `action` code and params with the i18n messages (English and French); the target name is user content and is not translated.
 - Failed and security rows use `--rc-error-soft` / `--ui-error` and `--rc-warning-soft` / `--ui-warning` for emphasis, always paired with an icon or a word, never colour alone.
+
+## Added with Image variants
+
+The full inventory with the Nuxt UI mapping is in [image-variants](screens/image-variants.md#component-inventory). New components: Variants table (and its mobile card row), Variant row (image detail), Variant form, Split comparison slider (`ImageCompare`, a custom component on a native range input, since Nuxt UI has no match), Stat tile, Bar list, Top-N list, Type-to-confirm dialog, Variant select, Variants badge, Filter, Request reference card. Alerts, toasts, dialogs, empty states and skeletons are reused as they are. The only token not already in the system is `--rc-on-sand`.