feat: Enhance #use directive for directories and cwd

The `#use` directive now supports referencing entire directories,
automatically including all `.myc` files within them. Additionally,
environments are now initialized with the current working directory as a
default search path, simplifying module resolution.

src/bin/ast.rs

@@ -42,9 +42,9 @@ struct Cli {
 
 fn main() {
     let cli = Cli::parse();
-    let mut env = Environment::new();
+    let mut env = Environment::new().with_cwd();
     env.optimization = !cli.no_opt;
-    
+
     // Load libraries (Now just search paths)
     for lib_path in &cli.lib {
         env.add_search_path(lib_path);