Refactor bound node types for clarity

Introduce generic `CompilerPhase` trait to unify different stages of the
bound AST. Rename `LocalSlot` to `VirtualId` and introduce `StackOffset`
for clearer distinction between compile-time and run-time addressing.
Update type aliases and implementations to reflect these changes.

src/ast/compiler/specializer.rs

@@ -1,4 +1,4 @@
-use crate::ast::compiler::bound_nodes::{Address, AnalyzedNode, BoundKind, Node, NodeMetrics};
+use crate::ast::compiler::bound_nodes::{Address, AnalyzedNode, AnalyzedPhase, BoundKind, Node, NodeMetrics, VirtualId};
 use crate::ast::types::{Purity, Signature, StaticType, Value};
 use std::cell::RefCell;
 use std::collections::HashMap;
@@ -6,16 +6,16 @@ use std::rc::Rc;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct MonoCacheKey {
-    pub address: Address,
+    pub address: Address<VirtualId>,
     pub arg_types: Vec<StaticType>,
 }
 
-pub type CompileFunc = Rc<dyn Fn(Rc<Node>, &[StaticType]) -> Result<(Value, StaticType), String>>;
+pub type CompileFunc = Rc<dyn Fn(Rc<Node<AnalyzedPhase>>, &[StaticType]) -> Result<(Value, StaticType), String>>;
 pub type RtlLookupFunc = Rc<dyn Fn(&str, &[StaticType]) -> Option<(Value, StaticType)>>;
 
 pub trait FunctionRegistry {
-    fn resolve(&self, addr: Address) -> Option<Rc<Node>>;
-    fn resolve_analyzed(&self, _addr: Address) -> Option<Rc<AnalyzedNode>> {
+    fn resolve(&self, addr: Address<VirtualId>) -> Option<Rc<Node<AnalyzedPhase>>>;
+    fn resolve_analyzed(&self, _addr: Address<VirtualId>) -> Option<Rc<AnalyzedNode>> {
         None
     }
 }