[CI] Add mypy Type Checking to Pre-commit Hook

[DsThakurRawat]

Description

The codebase uses type hints extensively, but they are not enforced during the commit process.

Task

• Update .pre-commit-config.yaml to include mirrors-mypy.
• Configure a basic mypy.ini (or section in pyproject.toml) that ignores missing imports for 3rd party libs.

[huynna12]

can i work on this issue?

[github-actions]

👋 Thanks for your interest in this issue!

This is a great place to start contributing 🎉

Before you begin, please read our contributing guide:
👉 https://github.com/FastCrest/tether/blob/main/CONTRIBUTING.md

Getting started

• Comment that you're working on it
• Follow the setup steps in CONTRIBUTING.md
• Open a PR when ready

If you get stuck, just ask here — happy to help! 🚀

[rylinjames]

Picked this up in #256: adds the mirrors-mypy pre-commit hook plus a basic pyproject.toml mypy config. CI is green; the PR is waiting on review/merge.

[rylinjames]

@huynna12 this landed in #256 and the issue is closed now. Thanks for offering to pick it up. If you want another scoped first issue, add me on Discord (romirj) and I can route you to one that is still open.

[huynna12]

@rylinjames Thanks for letting me know. I added you.