feat: Add --no-opt flag and a failing test case

Introduce a --no-opt flag to disable compiler optimizations and add a
new integration test case to reproduce a slot clash issue during
inlining.

src/bin/ast.rs

@@ -42,8 +42,8 @@ struct Cli {
 
 fn main() {
     let cli = Cli::parse();
-    let env = Environment::new();
-    // Use env.optimization setting if needed, though it's currently on by default
+    let mut env = Environment::new();
+    env.optimization = !cli.no_opt;
     
     // Load libraries
     for lib_path in &cli.lib {

src/integration_test.rs

@@ -756,4 +756,31 @@ mod tests {
                 .any(|m| m.contains("Invalid arguments for function call"))
         );
     }
+
+    #[test]
+    fn test_optimizer_inlining_slot_clash_repro() {
+        let mut env = Environment::new();
+        env.optimization = true;
+        
+        // This exactly mirrors err.myc structure.
+        // NOTE: We must use a dynamic call like (series :float) here. 
+        // Simple constants like (def history 100) might be constant-folded or 
+        // inlined as values by the optimizer before the slot-clash can occur.
+        // By using a series, we force the result into a local slot at runtime,
+        // which triggers the conflict when the inliner fails to remap slots correctly.
+        let source = r#"
+        (do
+          (def outer (fn [length] 
+            (do 
+              (def history (series :float)) 
+              (fn [val] length)
+            )
+          ))
+          ((outer 20) 5)
+        )
+        "#;
+        
+        let res = env.run_script(source).unwrap();
+        assert_eq!(format!("{}", res), "20");
+    }
 }