Remove unused system library and simplify environment initialization

The `system.myc` file, containing macros and core utilities, has been
removed as its functionality is now handled by an embedded string. This
simplifies the build process and eliminates a file that was no longer
strictly necessary.

Additionally, the `with_cwd()` method on the `Environment` has been
removed. The environment now automatically adds the current working
directory and its `rtl` subdirectory to the search paths during
initialization. This streamlines the setup for file-based usage and
ensures standard search paths are always considered.

src/bin/ast.rs

@@ -42,7 +42,7 @@ struct Cli {
 
 fn main() {
     let cli = Cli::parse();
-    let mut env = Environment::new().with_cwd();
+    let mut env = Environment::new();
     env.optimization = !cli.no_opt;
 
     // Load libraries (Now just search paths)
@@ -74,11 +74,6 @@ fn main() {
     }
 
     if let Some(script_str) = cli.eval {
-        if let Err(e) = env.preload_dependencies(&script_str, None) {
-            eprintln!("❌ Error resolving dependencies: {}", e);
-            std::process::exit(1);
-        }
-
         if cli.dump {
             match env.dump_ast(&script_str) {
                 Ok(dump) => println!("{}", dump),
@@ -92,11 +87,6 @@ fn main() {
     } else if let Some(file_path) = cli.file {
         match fs::read_to_string(&file_path) {
             Ok(content) => {
-                if let Err(e) = env.preload_dependencies(&content, Some(&file_path)) {
-                    eprintln!("❌ Error resolving dependencies for {:?}:\n{}", file_path, e);
-                    std::process::exit(1);
-                }
-
                 if cli.dump {
                     match env.dump_ast(&content) {
                         Ok(dump) => println!("{}", dump),