refactor: move ProgramVariableManager to Core, add config file support

- Move ProgramVariable and ProgramVariableManager from
  OpenNest.Posts.Cincinnati to OpenNest.Core/CNC (namespace OpenNest.CNC)
  so they can be used internally in nest programs
- Add parameterless constructor to CincinnatiPostProcessor that loads
  config from a .json file next to the DLL (creates defaults on first run)
- Enums serialize as readable strings (e.g., "Inches", "ControllerSide")
- Config file: OpenNest.Posts.Cincinnati.json in the Posts/ directory

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Posts.Cincinnati/CincinnatiPostProcessor.cs

@@ -1,23 +1,63 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Reflection;
 using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using OpenNest.CNC;
 
 namespace OpenNest.Posts.Cincinnati
 {
     public sealed class CincinnatiPostProcessor : IPostProcessor
     {
+        private static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            WriteIndented = true,
+            Converters = { new JsonStringEnumConverter() }
+        };
+
         public string Name => "Cincinnati CL-707";
         public string Author => "OpenNest";
         public string Description => "Cincinnati CL-707/CL-800/CL-900/CL-940/CLX family";
 
         public CincinnatiPostConfig Config { get; }
 
+        public CincinnatiPostProcessor()
+        {
+            var configPath = GetConfigPath();
+            if (File.Exists(configPath))
+            {
+                var json = File.ReadAllText(configPath);
+                Config = JsonSerializer.Deserialize<CincinnatiPostConfig>(json, JsonOptions);
+            }
+            else
+            {
+                Config = new CincinnatiPostConfig();
+                SaveConfig();
+            }
+        }
+
         public CincinnatiPostProcessor(CincinnatiPostConfig config)
         {
             Config = config;
         }
 
+        public void SaveConfig()
+        {
+            var configPath = GetConfigPath();
+            var json = JsonSerializer.Serialize(Config, JsonOptions);
+            File.WriteAllText(configPath, json);
+        }
+
+        private static string GetConfigPath()
+        {
+            var assemblyPath = typeof(CincinnatiPostProcessor).Assembly.Location;
+            var dir = Path.GetDirectoryName(assemblyPath);
+            var name = Path.GetFileNameWithoutExtension(assemblyPath);
+            return Path.Combine(dir, name + ".json");
+        }
+
         public void Post(Nest nest, Stream outputStream)
         {
             // 1. Create variable manager and register standard variables

OpenNest.Posts.Cincinnati/CincinnatiPreambleWriter.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using OpenNest;
+using OpenNest.CNC;
 
 namespace OpenNest.Posts.Cincinnati;
 

OpenNest.Posts.Cincinnati/ProgramVariable.cs

@@ -1,18 +0,0 @@
-namespace OpenNest.Posts.Cincinnati
-{
-    public sealed class ProgramVariable
-    {
-        public int Number { get; }
-        public string Name { get; }
-        public string Expression { get; set; }
-
-        public ProgramVariable(int number, string name, string expression = null)
-        {
-            Number = number;
-            Name = name;
-            Expression = expression;
-        }
-
-        public string Reference => $"#{Number}";
-    }
-}

OpenNest.Posts.Cincinnati/ProgramVariableManager.cs

@@ -1,43 +0,0 @@
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-namespace OpenNest.Posts.Cincinnati
-{
-    public sealed class ProgramVariableManager
-    {
-        private readonly Dictionary<int, ProgramVariable> _variables = new();
-
-        public ProgramVariable GetOrCreate(string name, int number, string expression = null)
-        {
-            if (_variables.TryGetValue(number, out var existing))
-                return existing;
-
-            var variable = new ProgramVariable(number, name, expression);
-            _variables[number] = variable;
-            return variable;
-        }
-
-        public List<string> EmitDeclarations()
-        {
-            return _variables.Values
-                .Where(v => v.Expression != null)
-                .OrderBy(v => v.Number)
-                .Select(v => $"{v.Reference}={v.Expression} ({FormatComment(v.Name)})")
-                .ToList();
-        }
-
-        private static string FormatComment(string name)
-        {
-            // "LeadInFeedrate" -> "LEAD IN FEEDRATE"
-            var sb = new StringBuilder();
-            foreach (var c in name)
-            {
-                if (char.IsUpper(c) && sb.Length > 0)
-                    sb.Append(' ');
-                sb.Append(char.ToUpper(c));
-            }
-            return sb.ToString();
-        }
-    }
-}