Show HN: Paganel – Data migration with a receipt you can verify later

Paganel comes from an old work problem: I had a large schema migration with lots of transformations and several environments to check. One of the main requirements was to validate whether the data had moved correctly, and I was not allowed to use any SaaS tools because it was forbidden for data to leave our network. Since I couldn't find any air-gapped tool that could do both the transformation and the verification (basic row counts aren't enough for transformed data), I had to write custom scripts for the entire process.Ever since then, the idea of automating complex migrations has stuck in my head, which led me to start building Paganel a year and a half ago.In Paganel, a migration is just a single declarative file. You specify where the data comes from and where it's going, and the rest goes in the same file: joins, filters, computed fields, and validation rules.If you are missing a specific source, sink, transform, or filter, you can easily extend Paganel by writing your own WASM plugin in Rust or JS. These execute inside a strict sandbox, so they don't have any filesystem or network access unless you allow it in the migration config.I also wanted to make large migrations…