Add live preview page to editor docs

[ethanpalm]

Documentation changes

This PR documents the live preview feature and applies some general 💅🏼 to the editor pages.

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For Reviewers

When reviewing documentation PRs, please consider:

✅ Technical accuracy

• Code examples work as written
• Commands and configurations are correct
• Links resolve to the right destinations
• Prerequisites and requirements are accurate

✅ Clarity and completeness

• Instructions are clear and easy to follow
• Steps are in logical order
• Nothing important is missing
• Examples help illustrate the concepts

✅ User experience

• A new user could follow these docs successfully
• Common gotchas or edge cases are addressed
• Error messages or troubleshooting guidance is helpful

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Note

Introduces documentation for live preview and streamlines related editor docs.

• Adds editor/live-preview.mdx with feature overview, comparison to preview deployments, and toolbar screenshot; links it in docs.json
• Refines copy and structure across editor/collaborate.mdx, editor/publish.mdx, editor/pages.mdx, editor/media.mdx, and editor/navigation.mdx (clearer steps, headings, and added Frames/screenshots)
• Tweaks editor/configurations.mdx formatting and removes the "Configure API documentation" section
• Updates editor/keyboard-shortcuts.mdx by removing the Ordered list shortcut row

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