feat(ai): add apply-to-editor actions for assistant code suggestions

[Divyansh2992]

Closes #853

Adds one-click apply actions for AI-generated editor replacements in the chat panel. When the assistant returns complete templatemarkApply, concertoApply, or jsonApply code blocks, users can apply them directly to the matching editor without copy-paste. The system prompt was also tightened so the assistant is more consistent about returning apply-ready code fences.

Changes

• update the AI chat panel to detect templatemarkApply, concertoApply, and jsonApply fenced code blocks and render an Apply to Editor button beneath each supported block
• wire apply actions to the existing editor store update flow so the matching editor is updated immediately and the preview rebuilds through the normal TemplateMark, Concerto, and JSON paths
• strengthen the AI system prompt so full editor replacements are returned with exact *Apply code fence tags, including coordinated multi-editor responses when needed

Flags

• manual verification completed by applying AI-generated TemplateMark, Concerto, and JSON suggestions from the chat panel and confirming editor and preview updates
• no new automated tests were added in this change; linting passed and the production build completed successfully
• success and error feedback is currently shown inline beneath the applied code block instead of through a toast notification

Screenshots

Related Issues

• Issue Add "Apply to Editor" button for AI code suggestions in chat panel #853

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname

[netlify]

✅ Deploy Preview for ap-template-playground ready!

Name	Link
🔨 Latest commit	080a416
🔍 Latest deploy log	https://app.netlify.com/projects/ap-template-playground/deploys/69ccb08af6e3900008e3f0e4
😎 Deploy Preview	https://deploy-preview-864--ap-template-playground.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[github-actions]

This PR is stale because it has been open 15 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[Divyansh2992]

@sanketshevkar @DianaLease @dselman can you please review my this pr, as this has been reported to be stale by github bot. So can you please it asap.