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- Add TestChain ecosystem with full protocol, DeFi, tools, wallet, bridge, and NFT support
- Add new Ethereum repositories covering DeFi, developer tools, NFT, oracle, DAO, and wallet projects
- Add Layer 2 ecosystems (Optimism, Arbitrum, Polygon, Base) and connect them to Ethereum
- Add missing Bitcoin ecosystem repositories including Lightning, DeFi, tools, wallets, bridges, oracles, and DAO
- Connect TestChain and all Layer 2s to Ethereum as parent ecosystem

Total: 4 new migration files with 50+ new repositories across 6 ecosystems

 Fixed Issues:
1. Removed duplicate TestChain ecosystem (was example only)
2. Fixed duplicate Polygon and Arbitrum ecosystems (already exist in 2017-2018)
3. Replaced fake repository URLs with real, existing repositories
4. Updated Layer 2 connections to use existing ecosystems properly

 Improvements:
- Ethereum repos now use real projects: Balancer, Curve, Yearn, OpenZeppelin, Hardhat, etc.
- Bitcoin repos now use real projects: Lightning Network, Bitcoin Core, RSK, etc.
- Layer 2 repos use real Optimism, Arbitrum, Polygon projects
- Only Base ecosystem added as new (others already exist)

Total: 3 corrected migration files with 25+ real repositories

- Add missing TestChain ecosystem migration file
- Update Ethereum repositories with corrected entries
- Fix Layer 2 ecosystem connections
- Update Bitcoin ecosystem with proper repository links

All migration files now properly formatted and complete.