feat: configure pre-commit hooks for cargo fmt and cargo clippy

[Jopsan-gm]

Title feat: configure pre-commit hooks for cargo fmt and cargo clippy

Description

This PR addresses issue #3 by setting up and configuring pre-commit hooks to automate code formatting and linting.

Closes #3

Changes

• Added .pre-commit-config.yaml containing hooks for cargo fmt and cargo clippy.
• Updated the root README.md with step-by-step instructions on how to install and configure pre-commit locally.
• Formatted and resolved pre-existing warnings in the Rust files (contracts/src/lib.rs and contracts/src/test.rs) to ensure the pre-commit hooks run and pass cleanly.
• Resolved a minor cargo warning by changing dev_dependencies to dev-dependencies in contracts/Cargo.toml.

Screenshots / Evidence

Below is the screenshot showing that the pre-commit hooks execute and pass successfully on commit:

[Jopsan-gm]

Hi @Queenode, PR ready for review! ;)

[Queenode]

Thank you for your contribution @Jopsan-gm .
Welldone