Core Contract Improvements & Security Enhancements

[TomasDmArg]

Description

This PR introduces major improvements to the ChatterPay smart contracts:

🏗 Infrastructure

• Reorganized folder structure
• Added integration tests
• Created test automation script
• Created core contracts ABI generation script
• Switched from API3 to Chainlink oracles

🔒 Security

• Limited unsafe execute function for transfers
• Added fee management system
• Implemented admin controls
• Enhanced error handling

⚡️ Features

• Added Uniswap integration (executeSwap)
• Implemented batch transfers
• Added price feed integration
• Finished fee collection and single transfers
• Enhanced fee calculations

📚 Documentation

• Added comprehensive docs for all contracts
• Documented testing strategy
• Added setup guides

🚨Breaking Changes

• Limited public execute function for transfers (modified transfers)
• Changed oracle integration from API3 to Chainlink
• Modified swap approach
• Added extra approach for transferAll
• Modified fee calculation mechanism

🧪Test Coverage

✅ Unit tests
✅ Integration tests
✅ Gas optimization tests
✅ Security tests

Resolves: #53, #54, #55, #56, #57, #58, #59, #60, #61, #63