Prevent sidebar tool buttons from flashing during collapse.
## What changed
- Clip the sidebar tool-buttons container during hover collapse so tab
labels don't render outside the header.
- Keep the existing width/opacity transition so the title still reclaims
space.
## Why
- Motivation: the hover-out transition shrinks the tool-buttons wrapper
to `w-0` while the tabs keep their intrinsic width, causing a brief
clipped flash on the right edge of the sidebar.
- Why this approach: clipping during the transition is the smallest
change that fixes the visual artifact without altering layout timing or
hover behavior.
- Tradeoffs / limitations: no functional change; the buttons are only
clipped while collapsing.
## Evidence
- Issues: n/a
- Tests: Not run (lint/typecheck only; not evidence)
- Screenshots/video:
https://github.com/user-attachments/assets/3af4d735-6330-4521-b4cf-45eb4b09f9ba
## References
- Related PRs: n/a
## Summary
Unify the current sidebar tabs, structurally and aesthetically.
## Changes
- Removes the Assets only Layout
- Standardizes the title styling and spacing across the tabs.
## Review Focus
<!-- Critical design decisions or edge cases that need attention -->
<!-- If this PR fixes an issue, uncomment and update the line below -->
<!-- Fixes #ISSUE_NUMBER -->
## Screenshots (if applicable)
<!-- Add screenshots or video recording to help explain your changes -->
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7215-WIP-Sidebar-Tabs-component-and-style-alignment-2c26d73d3650817193bfd752e0d0bbde)
by [Unito](https://www.unito.io)
* temp: move tailwind calls out of the layer
* temp: ts tailwind config
* upgrade: Tailwind v4
This got a little out of hand.
Had to add a relative reference to the stylesheet in any component that uses @apply instead of the utility classes directly.
* upgrade: bg-opacity is now a modifier
* fix: Classic menu buttons assume a border
* Update test expectations [skip ci]
* fix: New preflight removal pattern
* fix: Skeletons don't have skin
* Update test expectations [skip ci]
* fix: Missing @reference
* [auto-fix] Apply ESLint and Prettier fixes
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Co-authored-by: GitHub Action <action@github.com>
