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/assets/palettes/dark.json

@@ -22,7 +22,7 @@
     },
     "litegraph_base": {
       "BACKGROUND_IMAGE": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAGQAAABkCAIAAAD/gAIDAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAQBJREFUeNrs1rEKwjAUhlETUkj3vP9rdmr1Ysammk2w5wdxuLgcMHyptfawuZX4pJSWZTnfnu/lnIe/jNNxHHGNn//HNbbv+4dr6V+11uF527arU7+u63qfa/bnmh8sWLBgwYJlqRf8MEptXPBXJXa37BSl3ixYsGDBMliwFLyCV/DeLIMFCxYsWLBMwSt4Be/NggXLYMGCBUvBK3iNruC9WbBgwYJlsGApeAWv4L1ZBgsWLFiwYJmCV/AK3psFC5bBggULloJX8BpdwXuzYMGCBctgwVLwCl7Be7MMFixYsGDBsu8FH1FaSmExVfAxBa/gvVmwYMGCZbBg/W4vAQYA5tRF9QYlv/QAAAAASUVORK5CYII=",
-      "CLEAR_BACKGROUND_COLOR": "#222",
+      "CLEAR_BACKGROUND_COLOR": "#141414",
       "NODE_TITLE_COLOR": "#999",
       "NODE_SELECTED_TITLE_COLOR": "#FFF",
       "NODE_TEXT_SIZE": 14,
@@ -52,7 +52,7 @@
     "comfy_base": {
       "fg-color": "#fff",
       "bg-color": "#202020",
-      "comfy-menu-bg": "#11141a",
+      "comfy-menu-bg": "#171718",
       "comfy-menu-secondary-bg": "#303030",
       "comfy-input-bg": "#222",
       "input-text": "#ddd",