Migrate from Poetry to uv

[t41372]

This pull request migrates the project from Poetry to UV, following the discussion in #420.

Note: I have not updated the GitHub Actions workflows yet, as I’m less familiar with CI/CD pipelines. The current workflows still rely on Poetry, so we’ll need to address that before merging to ensure everything runs smoothly.

✅ What’s been done:

• Migrated both graphiti-core and graph-service to use UV for dependency management.
• Updated the Dockerfile to use UV. This also resolves #439; the image now builds and runs successfully.
• Updated README and CONTRIBUTING docs to reflect the switch to UV.

🚧 What’s not done:

• GitHub Actions workflows are still using Poetry and have not been migrated to UV.

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[!IMPORTANT] Migrated project from Poetry to UV for dependency management, updating Dockerfile, Makefile, and documentation, but GitHub Actions workflows still need migration.

• Dependency Management:
  • Migrated from Poetry to UV in graphiti-core and graph-service.
  • Updated pyproject.toml to use UV's dependency group format.
• Dockerfile:
  • Replaced Poetry with UV for building and installing dependencies.
  • Added UV-specific environment variables for performance.
• Makefile:
  • Replaced Poetry commands with UV commands for installing, testing, and linting.
• Documentation:
  • Updated README.md and CONTRIBUTING.md to reflect the switch to UV.
• Pending:
  • GitHub Actions workflows still use Poetry and need migration to UV.

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