Add PartialEq to BoundKind and Value

Implement PartialEq for BoundKind to allow for structural equality
checks during optimization. This enables the optimizer to terminate
early when a node no longer changes.

Also, implement PartialEq for Value to facilitate comparisons between
different Value variants.

src/ast/compiler/optimizer.rs

@@ -24,7 +24,9 @@ impl Optimizer {
         let mut current = node;
         for _ in 0..self.max_passes {
             let next = self.visit_node(current.clone());
-            // TODO: Structural equality check to stop early
+            if next == current {
+                break;
+            }
             current = next;
         }
         current