✅ Enable Trusted Publisher for PyPI Publishing via GitHub Actions

[tavallaie]

This PR updates our GitHub Actions to use Trusted Publisher for PyPI publishing. We no longer need POETRY_PYPI_TOKEN_PYPI because we’ve fully moved to uv and Trusted Publisher authentication.

Key Changes:

• ✅ Removed POETRY_PYPI_TOKEN_PYPI
• 🔐 Added id-token write permission for OIDC
• 🧹 Removed unused env block in publish step
• 🔄 Upgraded to actions/checkout v5 and setup-uv v6
• 🐍 Using Python 3.13 but dependency setup unchanged, lint and test jobs unaffected