refactor(contracts): remove deprecated AIPowerRental contract in favor of bounty system

- Delete AIPowerRental.sol (566 lines) - replaced by AgentBounty.sol
- Remove rental agreement system with provider/consumer model
- Remove performance metrics and SLA tracking
- Remove dispute resolution mechanism
- Remove ZK-proof verification for performance
- Remove provider/consumer authorization system
- Bounty system provides superior developer incentive structure

contracts/.env.example

@@ -0,0 +1,18 @@
+# AITBC Developer Ecosystem - Environment Configuration
+# Copy this file to .env and update with your actual values
+
+# Network Configuration
+PRIVATE_KEY=your_private_key_here
+INFURA_PROJECT_ID=your_infura_project_id
+ETHERSCAN_API_KEY=your_etherscan_api_key
+
+# Network URLs
+SEPOLIA_URL=https://sepolia.infura.io/v3/${INFURA_PROJECT_ID}
+GOERLI_URL=https://goerli.infura.io/v3/${INFURA_PROJECT_ID}
+MAINNET_URL=https://mainnet.infura.io/v3/${INFURA_PROJECT_ID}
+
+# Security Notes:
+# - Never commit your actual private key to version control
+# - Use a dedicated deployer account for contracts
+# - Keep your private key secure and use a hardware wallet for mainnet
+# - Use environment variables or a secure secrets manager