Refactor environment to use stack-based scoping

The commit rewrites the environment to use a stack of hash maps for
managing variable scopes. This replaces the old parent-reference
approach with a simpler and more efficient stack-based model.

Key changes: - Rename Environment to EnvironmentStack - Store scopes in
a Vec of HashMaps - Add push/pop scope operations for block handling -
Update interpreter to properly manage scope lifetimes - Clean up error
handling with helper functions

src/logging/display_ast.rs

@@ -3,10 +3,7 @@
 //! This module provides elegant and functional printing capabilities for AST objects,
 //! inspired by Rust's debug formatting but optimized for readability and analysis.
 
-use crate::frontend::{
-    ast::{AstNode, AstNodeKind, Expr, Stmt},
-    source_registry::SourceSlice,
-};
+use crate::frontend::ast::{AstNode, AstNodeKind, Expr, Stmt};
 use std::fmt::{self, Write};
 
 /// Configuration for pretty printing output
@@ -39,6 +36,7 @@ impl Default for PrettyConfig {
     }
 }
 
+#[allow(dead_code)]
 impl PrettyConfig {
     /// Create a compact configuration
     pub fn compact() -> Self {
@@ -471,6 +469,7 @@ impl<T: AstNodeKind + fmt::Debug + fmt::Display + PrettyPrint> PrettyPrint for A
 }
 
 // Extension trait for convenience methods
+#[allow(dead_code)]
 pub trait PrettyPrintExt {
     fn pretty(&self) -> String;
     fn pretty_compact(&self) -> String;
@@ -531,24 +530,3 @@ impl<T: AstNodeKind + fmt::Debug + fmt::Display + PrettyPrint> PrettyPrintExt fo
         pretty_print_with_config(self, config)
     }
 }
-
-/// Convenience functions for quick pretty printing
-pub fn pretty_expr(expr: &Expr) -> String {
-    pretty_print(expr)
-}
-
-pub fn pretty_stmt(stmt: &Stmt) -> String {
-    pretty_print(stmt)
-}
-
-pub fn pretty_expr_compact(expr: &Expr) -> String {
-    pretty_print_with_config(expr, &PrettyConfig::compact())
-}
-
-pub fn pretty_stmt_compact(stmt: &Stmt) -> String {
-    pretty_print_with_config(stmt, &PrettyConfig::compact())
-}
-
-pub fn pretty_tree<T: PrettyPrint>(item: &T) -> String {
-    pretty_print_with_config(item, &PrettyConfig::tree())
-}