ko1/astro: ASTro: AST-based Reusable Optimization framework

ASTro is an optimization framework based on Abstract Syntax Trees (ASTs). It provides a reusable infrastructure for generating optimized code fragments through partial evaluation of AST interpreters, emitting C source as the output of specialization and delegating native code generation to a mature C compiler (gcc/clang). The companion tool ASTroGen (lib/astrogen.rb) automatically generates an interpreter (evaluator), a dispatcher, allocators, Merkle-tree hash functions, a partial evaluator (specializer), a dumper, and node-replacement helpers from a node.def file that defines node types and their behaviors in C code.