feat: add EditTools.cs to implement file manipulation functions like replace_lines, delete_range, and batch_edit, updating README.md to reflect new tools and command descriptions.

Tools/EditTools.cs

@@ -352,8 +352,8 @@ internal static partial class EditTools
                 }
             }
 
-            // Sort operations bottom-to-top (by start index descending) for safe application
-            var sortedOps = resolvedOps.OrderByDescending(x => x.StartIdx).ToList();
+            // Sort operations top-to-bottom (by start index ascending) because we build a new list sequentially
+            var sortedOps = resolvedOps.OrderBy(x => x.StartIdx).ToList();
 
             // Apply all operations to a single buffer
             var result = new List<string>(lines.Length);