Add cacheflow to Project/Tooling Updates

[thaicn1712]

cacheflow: exact and semantic response caching for graph-flow LLM tasks — wraps a graph_flow::Task, skips the repeat LLM call on a cache hit, cosine-similarity semantic matching via a pluggable Embedder trait.

[github-actions]

Thank you for your contribution to This Week in Rust! Our automated checks found some possible issues with these changes:

Link check

• warning: link https://github.com/thaicn1712/cacheflow is directly to a GitHub repo; please double check our guidelines here: https://github.com/rust-lang/this-week-in-rust#projectstooling-updates

You can see more details here: https://github.com/rust-lang/this-week-in-rust/actions/runs/31241904437

[nellshamrell]

Hello there!

We currently only allow one link submission to the Projects/Tooling section per contributor per week. Please pick one of the links you have submitted this week and open a new pull request with only that link. Closing the rest of the pull requests in the meantime.

Also please know that we are making changes to the link submission/review process for the Projects/Tooling section starting next issue. Please see this GitHub issue for more information.