Implement uv.lock file and cache uv package store in CI workflows

[dlqqq]

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We should implement proper dependency locking using uv.lock files and cache the uv package store across GitHub Actions workflow runs to improve CI performance and reproducibility.

PR #1392 introduces uv to the project, but we're not yet leveraging uv's caching capabilities or lockfile functionality. By implementing caching and using lockfiles, we can significantly reduce build times and ensure consistent dependency versions across different workflow runs. The GitHub Actions caching integration for uv is well-documented and provides both built-in and manual caching options.

Reference: https://docs.astral.sh/uv/guides/integration/github/#caching