e757b453a4
Introduces a new AST emitter module responsible for serializing AST nodes back into Myc source code. This emitter preserves leading comments and whitespace, enabling a round-trip guarantee for the parser and emitter. The documentation in `docs/BNF.md` has been updated to reflect the new syntax rules for comments, including single-line comments (`;`) and documentation comments (`;;`). The rules clarify that comments must be whole lines and that inline comments are disallowed. The lexer and AST node structures have been updated to accommodate `CommentLine` variants, allowing for different types of comments (regular, documentation, and blank lines) to be stored and processed. A new test suite `tests/comment_roundtrip.rs` has been added to verify the round-trip property of the parser and emitter across all example `.myc` files. This test ensures that parsing source code, emitting it, and then parsing the emitted code again results in the same output string. The `ast.rs` binary now includes a `--emit` flag that uses the new emitter to output the parsed source code, facilitating debugging and testing of the emitter itself.