feat(viewer): fit the header on one row

[hyamero]

The header stacked breadcrumb, title and tabs on three rows (~150px) and repeated itself: the kind appeared in both the breadcrumb and the badge.

• Title, kind badge, view tabs and counts now share one row (~56px), so the canvas gains ~90px of height.
• The breadcrumb is removed.
• The title is 20px and truncates at 45% of the row.
• Tabs scroll sideways instead of wrapping, and the active-tab underline sits on the header rule.
• The counts hide below the md breakpoint.
• A view's caption still shows on its own line under the header, only when that view has one.
• Visual baselines were regenerated in CI (workflow_dispatch update-visual).

[github-actions]

🎉 This PR is included in version 0.1.0-rc.1 🎉

The release is available on:

• v0.1.0-rc.1
• GitHub release

Your semantic-release bot 📦🚀

[github-actions]

🎉 This PR is included in version 0.1.0 🎉

The release is available on:

• v0.1.0
• GitHub release

Your semantic-release bot 📦🚀