Refactor: Move compiler node definitions to src/ast/nodes

The `bound_nodes.rs` file has been removed and its contents have been
moved to `src/ast/nodes.rs`. This consolidates all AST node definitions
into a single module, improving organization and maintainability.

The `compiler` modules now import these definitions from
`crate::ast::nodes` instead of `crate::ast::compiler::bound_nodes`.

src/ast/vm.rs

@@ -1,4 +1,4 @@
-use crate::ast::compiler::bound_nodes::{Address, AnalyzedNode, ExecNode, IdentifierBinding, NodeKind, StackOffset};
+use crate::ast::nodes::{Address, AnalyzedNode, ExecNode, IdentifierBinding, NodeKind, StackOffset};
 use crate::ast::types::{Object, Value};
 use std::any::Any;
 use std::cell::RefCell;