meta/rocksdb ? reverse-engineered prompt

Build me an embeddable persistent key value store in C++ that can be used as the core storage layer for a fast database.

I want it to be simple to open a database, put and get values, delete keys, and keep data on disk so it survives restarts. It should be tuned for fast writes and good read performance, with support for larger data sets and background compaction so files do not grow out of control. Please make the public API clean and keep internal details hidden, and include a few working examples that show how to use it from an application.

If you need to check current best practices or docs while building, look them up online. Also add a basic test setup so I can verify it works, and make sure the project builds cleanly on a normal modern C++ toolchain.