Add Introducing Toolbars blog post

[elnelson575]

Summary

• New blog post introducing the toolbar components in bslib 0.11.0 (R) and py-shiny 1.6.0 (Python), with dual-language examples throughout
• Code blocks render as static highlighted fences via execute: eval: false — no runtime needed
• Closes the open ask for a "what else is new" pointer with a closing callout linking the bslib and py-shiny changelogs

Test plan

• Open the Netlify preview at /blog/2026-05-15_introducing-toolbars/
• Verify TOC callout anchors all jump to the right H2 sections
• Toggle the R / Python tabs and confirm "Complete app code" details show the matching language inside each tab
• Confirm the eight bslib + py-shiny reference links in the components table resolve
• Confirm the bslib changelog and py-shiny CHANGELOG links in the closing callout resolve
• Spot-check images and demo.mov render

[netlify]

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[github-actions]

Publishing checklist

• Get a review — request at least one reviewer on this PR
• Check your post — once the deploy preview is ready, a comment will appear with direct links to your post
• Check the blog listing — confirm your post appears with the correct title, image, and description
• Merge — once everything looks good and you have an approving review, merge to main

[github-actions]

🚀 Deployed on https://6a1711dddc07b64765176d92--posit-open-source.netlify.app

[github-actions]

Blog YAML Checks

content/blog/introducing-toolbars/index.md

• ⚠️ date is in the past (2026-05-26). Post will publish immediately on merge.

Summary: 1 files checked, 1 warnings

[github-actions]

Preview links

• /blog/2026-05-26_introducing-toolbars/

Blog listing: https://6a1711dddc07b64765176d92--posit-open-source.netlify.app/blog/
Full site: https://6a1711dddc07b64765176d92--posit-open-source.netlify.app