Add migration tooling for extracting coding-challenges to separate repository

[Copilot]

The coding-challenges folder needs to be extracted into a standalone public repository at mbianchidev/coding-challenges for better organization and discoverability.

Changes

Migration automation (scripts/migrate-coding-challenges.sh)

• Copies coding-challenges content with proper handling of hidden files
• Initializes git repository with generated README, LICENSE, .gitignore, and CONTRIBUTING.md
• Dynamic copyright year generation for future-proofing

Documentation

• MIGRATION_GUIDE.md: Three migration approaches (automated, history-preserving, manual) with troubleshooting
• QUICKSTART.md: One-liner execution reference
• coding-challenges/README.md: Migration notice redirecting to new repository
• Updated main README.md with prominent link to new repository location

Usage

./scripts/migrate-coding-challenges.sh
cd /tmp/coding-challenges-repo
git add . && git commit -m "Initial commit"
gh repo create mbianchidev/coding-challenges --public --source=. --remote=origin --push

The script generates a complete repository structure ready for immediate publishing to GitHub.

Original prompt

Create a separate repo in mbianchidev (public) with the content of coding-challenges

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