Refactor: Analyze node purity and recursion

The Analyzer has been refactored to decorate `TypedNode`s with their
purity and recursion status. This involves creating a new `AnalyzedNode`
type and a `NodeMetrics` struct to hold this information. The `Analyzer`
now returns an `AnalyzedNode` instead of a separate `Analysis` struct.
This change lays the groundwork for future optimizations and analysis
passes.

src/ast/compiler/bound_nodes.rs

@@ -27,6 +27,17 @@ pub type BoundNode<T = ()> = Node<BoundKind<T>, T>;
 /// Type alias for a node that has been fully type-checked.
 pub type TypedNode = BoundNode<StaticType>;
 
+/// Metrics collected during the analysis phase.
+#[derive(Debug, Clone, PartialEq)]
+pub struct NodeMetrics {
+    pub original: Rc<TypedNode>,
+    pub purity: crate::ast::types::Purity,
+    pub is_recursive: bool,
+}
+
+/// Type alias for a node that has been analyzed.
+pub type AnalyzedNode = BoundNode<NodeMetrics>;
+
 #[derive(Debug, Clone)]
 pub enum BoundKind<T = ()> {
     Nop,