[backport core/1.30]: UI color updates & tweaks (#6679)

## Summary
Backports PR #6381 (UI color updates & tweaks) to core/1.30 branch.

This includes:
- Text readability improvements
- Semantic color token consistency updates
- UI element styling refinements
- Component import path fixes (ComfyLogoTransparent → ComfyLogo)

## Merge Conflicts Resolved
- **ComfyMenuButton.vue**: Accepted cherry-picked version with import
changes
- **20 browser test snapshots**: Used backportee's copy as instructed

**Original commit**: fd236b3587

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6679-Backport-PR-6381-to-core-1-30-UI-color-updates-tweaks-2aa6d73d3650815689defd191e3dd86e)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: github-actions <github-actions@github.com>

src/components/graph/selectionToolbox/RefreshSelectionButton.vue

@@ -7,7 +7,7 @@
     data-testid="refresh-button"
     @click="refreshSelected"
   >
-    <i class="icon-[lucide--refresh-cw] h-4 w-4" />
+    <i class="icon-[lucide--refresh-cw] size-4" />
   </Button>
 </template>