🔄 Implement In-Place Merge Sort (Without Extra Array)

Description:
Most implementations of merge sort use extra space to merge arrays. For this issue, implement an in-place merge sort that:

Does not use additional arrays during the merge step

Uses index manipulation or swaps to keep space usage minimal

Includes proper time and space complexity in comments

Adds sample input/output in a README.md inside your language folder

📁 Example Path: sorting/in-place-merge-sort/in-place-merge-sort.py (or .cpp, .js, etc.)
📘 Difficulty: Intermediate
🛠 Languages: Your choice (Python, C++, JavaScript, etc.)