Refactor: Replace optimization level with boolean flag

The optimizer now uses a simple boolean flag (`optimization`) instead of
an `optimization_level` (u32). This simplifies the optimizer's logic and
makes it easier to enable or disable optimizations.

The command-line interface and internal testing have been updated to
reflect this change.

src/main.rs

@@ -95,7 +95,7 @@ impl CompilerApp {
 
         // Reset environment for a fresh run
         self.env = Environment::new();
-        self.env.optimization_level = 2;
+        self.env.optimization = true;
 
         let res = (|| -> Result<(myc::ast::types::Value, std::time::Duration), String> {
             let start_run = std::time::Instant::now();
@@ -157,7 +157,7 @@ impl CompilerApp {
 
     fn dump_ast(&mut self) {
         self.env = Environment::new();
-        self.env.optimization_level = 2; // Enable optimization for AST dump
+        self.env.optimization = true; // Enable optimization for AST dump
         match self.env.dump_ast(&self.source_code) {
             Ok(dump) => {
                 self.output_log = format!("--- BOUND AST DUMP ---\n\n{}", dump);