update minimap and canvas bg to use menu color tokens (#6589)

Update minimap and graph canvas menu (bottom right) to use menu tokens.
Change canvas BG color on default dark theme.

<img width="3840" height="2029" alt="image"
src="https://github.com/user-attachments/assets/6d168981-df27-40c0-829c-59150b8a6a12"
/>


┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6589-wip-Style-graph-canvas-color-2a26d73d365081cb88c4c4bdb2b6d3a5)
by [Unito](https://www.unito.io)

---------

Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/components/common/UserAvatar.vue

@@ -1,6 +1,6 @@
 <template>
   <Avatar
-    class="bg-gray-200 dark-theme:bg-[var(--interface-panel-selected-surface)]"
+    class="bg-interface-panel-selected-surface"
     :image="photoUrl ?? undefined"
     :icon="hasAvatar ? undefined : 'icon-[lucide--user]'"
     :pt:icon:class="{ 'size-4': !hasAvatar }"