Floating Menus - UI rework (#5980)

## Summary

Enhancing and further modernizing the UI, giving users more usable area
whilst keeping farmiliar positioning and feel of elements.

## Changes

- **What**: Significant restructure of the UI elements, changing
elements from large blocks to floating elements, updating:
- Side toolbar menu (floating style, supports small/normal mode,
combines to scroll on height overflow)
- Bottom tabs panel (floating style, tabs redesigned)
- Action bar (support for docking/undocking menu)
    - Added login/user menu button to top right
- Restyled breadcrumbs (still collapse when overflows)
- Add litegraph support for fps info position (so it isn't covered by
the sidebar)

- **Breaking**: 
- Removed various elements and added new ones, I have tested custom
sidebars, custom actions, etc but if scripts are inserting elements into
"other" elements they may have been (re)moved.
- Remove support for bottom menu
- Remove support for 2nd-row tabs

## Screenshots 
<img width="1116" height="907" alt="ui"
src="https://github.com/user-attachments/assets/b040a215-67d3-4c88-8c4d-f402a16a34f6"
/>


https://github.com/user-attachments/assets/571dbda5-01ec-47e8-b235-ee1b88c93dd0

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5980-Floating-Menus-UI-rework-2866d73d3650810aac60cc1afe979b60)
by [Unito](https://www.unito.io)

---------

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

browser_tests/tests/actionbar.spec.ts

@@ -116,9 +116,10 @@ test.describe('Actionbar', () => {
   test('Can dock actionbar into top menu', async ({ comfyPage }) => {
     await comfyPage.page.dragAndDrop(
       '.actionbar .drag-handle',
-      '.comfyui-menu',
+      '.actionbar-container',
       {
-        targetPosition: { x: 0, y: 0 }
+        targetPosition: { x: 50, y: 20 },
+        force: true
       }
     )
     expect(await comfyPage.actionbar.isDocked()).toBe(true)