smartcontracts

Remove SMART_CONTRACT_TASKS.md file, which contained detailed specifications for the smart contract tasks and functionalities.

Add challenge functionality to GoalPledgeEscrow contract, including structures for challenges and participants, event emissions, and methods for creating, joining, completing, resolving, and claiming winnings from challenges. Implement beneficiary management for goal stakes.

Update GoalPledgeEscrow contract to include goal description and modify event emission; add foundry.lock file for dependency management.

Add submodule for forge-std library

init goalpledgesmartcontracts