Add mcp-repl announcement post

[t-kalinowski]

Summary

Adds a new announcement post for mcp-repl, explaining why persistent, sandboxed R and Python sessions matter for MCP-capable agents and how to install the tool.

User-facing changes

• Adds the Announcing mcp-repl blog post.
• Adds a 16:9 hero graphic for the post.
• Adds an mcp-repl software page so the post links cleanly through site taxonomy.

Internal changes

• Adds blog frontmatter for author, topics, languages, software, source, tags, and image alt text.
• Adds software metadata for mcp-repl, including repository, language, topic, and release metadata.

[github-actions]

Publishing checklist

• Get a review — you're responsible for requesting one. Any colleague with Write access can approve; if your PR touches files outside a post folder, the assigned code owner's approval is also required before merging
• 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

[netlify]

✅ Deploy Preview for posit-open-source canceled.

Name	Link
🔨 Latest commit	29cc618
🔍 Latest deploy log	https://app.netlify.com/projects/posit-open-source/deploys/6a442c17078a6a000837ab2c

[github-actions]

🚀 Deployed on https://6a442ce5b989accbeab3f108--posit-open-source.netlify.app

[github-actions]

Blog YAML Checks

✅ All 1 posts passed.

[github-actions]

Preview links

• /blog/2026-06-30_announcing-mcp-repl/
• /software/mcp-repl/

Blog listing: https://6a442ce5b989accbeab3f108--posit-open-source.netlify.app/blog/
Full site: https://6a442ce5b989accbeab3f108--posit-open-source.netlify.app