Fix-issues

[shanberg]

• Adds shift-click (sidebar) open behavior to inline ref breadcrumbs
• Restores missing linked refs in block page
• Moves permalink message to new toast component
• Page menu appears to on right of title, not left, so we don't need so much left/right padding around pages
• Inline ref spacing improved
• Inline presence has tooltips, so we can tuck more away and they don't take as much space, all so that they can live inside the block content area and not fall off the edge in the sidebar
• shift-clicking inline ref breadcrumbs opens them in sidebar
• new 404 page

[vercel]

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