Clean LocalFhenix deployments before start

[giwaov]

Summary

• clean stale deployments/localfhenix artifacts by default before starting LocalFhenix
• keep an opt-out by passing clean=false
• update the Docker package tests and README to reflect the new default

Closes #5

Testing

• pnpm --filter fhenix-hardhat-docker run build
• pnpm --filter fhenix-hardhat-docker run lint
• pnpm --filter fhenix-hardhat-docker run test (fails locally because Docker is not installed: 'docker' is not recognized as an internal or external command)