feat: Implement closure cracking and inlining

Introduces a new optimizer pass that can "crack" closures, allowing for
more aggressive specialization. It also enables inlining of upvalues
that point to immutable global variables. This removes overhead for
higher-order functions and currying when arguments are statically
resolvable.

src/bin/ast.rs

@@ -30,11 +30,16 @@ struct Cli {
     /// Run with TracingObserver enabled
     #[arg(short, long)]
     trace: bool,
+
+    /// Optimization level (0: None, 1: Cracking, 2: Aggressive)
+    #[arg(short, long, default_value_t = 0)]
+    opt: u32,
 }
 
 fn main() {
     let cli = Cli::parse();
     let mut env = Environment::new();
+    env.optimization_level = cli.opt;
 
     if cli.bench || cli.update_bench {
         if cfg!(debug_assertions) {