Configures Reqnroll (the canonical .NET BDD framework) - install via `dotnet add package Reqnroll`, author `.feature` files in Gherkin, write step bindings as `[Given/When/Then]`-decorated methods in any C# class, runs via `dotnet test`. Reqnroll is the SpecFlow successor (SpecFlow reached end-of-life 2024-12-31); covers the SpecFlow-to-Reqnroll migration path, and references/specflow-legacy.md maintains not-yet-migrated SpecFlow projects. Use for .NET projects starting BDD, migrating from SpecFlow, or maintaining legacy SpecFlow suites.