fixture: create automated local setup shell script

[devmocrea]

Description

Add a setup.sh script to the root directory. The script should automatically bootstrap the local Hardhat and Clarinet dev environments in one command.

Technical Specification

• Create setup.sh in the root folder.
• Add logic to copy .env.example to .env.local, run pnpm install, compile smart contracts, and print instructions.

Acceptance Criteria

• Running bash setup.sh bootstraps the entire developer environment cleanly.