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/compiler/macros.rs

@@ -642,7 +642,7 @@ impl<E: MacroEvaluator> MacroExpander<E> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::ast::compiler::bound_nodes::Address;
+    use crate::ast::nodes::Address;
     use crate::ast::compiler::Binder;
     use crate::ast::parser::Parser;
     use crate::ast::types::{Object, Value};
@@ -788,7 +788,7 @@ mod tests {
         locals.insert(
             Symbol::from("*"),
             crate::ast::compiler::binder::LocalInfo {
-                addr: Address::Local(crate::ast::compiler::bound_nodes::VirtualId(0)),
+                addr: Address::Local(crate::ast::nodes::VirtualId(0)),
                 identity: crate::ast::types::NodeIdentity::new(crate::ast::types::SourceLocation {
                     line: 0,
                     col: 0,