boa-cat 0.2.0

Tree-walking ECMAScript interpreter built on ecma-syntax-cat. Evaluates Script programs to Values with a persistent heap and lexical environment, plus native (Rust-implemented) callables for embedder-supplied built-ins. No mut, no Rc/Arc, no interior mutability, no panics, exhaustive matches. Comp-cat-rs reformulation of the Boa engine core, targeting Tauri integration.