🧹 Delete duplicate old index HTML file

[pauloblikstein]

🎯 What: Deleted the duplicate old file summer-studio/index-old.html.
💡 Why: It's an old file that was duplicated, not referenced anywhere, and likely dead code. Removing it improves codebase maintainability and reduces clutter.
✅ Verification: Verified by checking that there were no references to index-old.html in the rest of the codebase, ensuring it's not depended upon. Also passed a code review.
✨ Result: The codebase is cleaner and doesn't contain duplicated, stale code, reducing confusion for future developers.

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PR created automatically by Jules for task 4480767099242190015 started by @pauloblikstein

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