Refactor: Migrate to clap for CLI argument parsing

The project now uses the `clap` crate for handling command-line
arguments, replacing the previous manual parsing approach. This includes
adding `clap` as a dependency and creating a `Cli` struct to define the
command-line interface. The `main` function has been updated to parse
these arguments and handle file input or direct script evaluation.

Cargo.toml

@@ -1,8 +1,9 @@
 [package]
-name = "Ast"
+name = "myc"
 version = "0.1.0"
 edition = "2024"
 
 [dependencies]
 eframe = "0.33.3"
 lazy_static = "1.4.0"
+clap = { version = "4.5", features = ["derive"] }