refactor: Relocate BinFileSaver to CutList.Core with report generation

Move BinFileSaver from CutList/Services to CutList.Core namespace for
reuse by MCP server. Add GenerateReport() method that returns formatted
text instead of only writing to file. Refactor to use TextWriter base
class for flexibility.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CutList/Forms/ResultsForm.cs

@@ -1,5 +1,4 @@
 using CutList.Core;
-using CutList.Services;
 
 namespace CutList.Forms
 {

CutList/Services/BinFileSaver.cs

@@ -1,131 +0,0 @@
-using CutList.Core;
-using CutList.Core.Formatting;
-using System.Diagnostics;
-
-namespace CutList.Services
-{
-    public class BinFileSaver
-    {
-        private readonly IEnumerable<Bin> _bins;
-
-        private int PaddingWidthOfItemLength { get; set; }
-
-        public bool OpenFileAfterSave { get; set; }
-
-        public BinFileSaver(IEnumerable<Bin> bins)
-        {
-            _bins = bins ?? throw new ArgumentNullException(nameof(bins));
-        }
-
-        public void SaveBinsToFile(string file)
-        {
-            using (var writer = new StreamWriter(file))
-            {
-                writer.AutoFlush = true;
-
-                PaddingWidthOfItemLength = _bins
-                    .SelectMany(b => b.Items)
-                    .Select(i => FormatHelper.ConvertToMixedFraction(i.Length).Length)
-                    .DefaultIfEmpty(0)
-                    .Max();
-
-                WriteHeader(writer);
-
-                var id = 1;
-                foreach (var bin in _bins)
-                {
-                    WriteBinSummary(writer, bin, id++);
-                }
-
-                WriteFinalSummary(writer);
-            }
-
-            if (OpenFileAfterSave)
-            {
-                OpenFile(file);
-            }
-        }
-
-        private void OpenFile(string file)
-        {
-            try
-            {
-                Process.Start("notepad.exe", file);
-            }
-            catch
-            {
-                Process.Start(file);
-            }
-        }
-
-        private void WriteHeader(StreamWriter writer)
-        {
-            var totalBars = _bins.Count();
-            var totalItems = _bins.Sum(b => b.Items.Count);
-
-            writer.WriteLine("CUT LIST");
-            writer.WriteLine($"Date: {DateTime.Now:g}");
-            writer.WriteLine($"Total stock bars needed: {totalBars}");
-            writer.WriteLine($"Total pieces to cut: {totalItems}");
-            writer.WriteLine();
-        }
-
-        private void WriteBinSummary(StreamWriter writer, Bin bin, int id)
-        {
-            var stockLength = FormatHelper.ConvertToMixedFraction(bin.Length);
-            var dropLength = FormatHelper.ConvertToMixedFraction(bin.RemainingLength);
-
-            writer.WriteLine(new string('─', 50));
-            writer.WriteLine($"BAR #{id}  -  Start with {stockLength}\" stock");
-            writer.WriteLine();
-            writer.WriteLine("  Cut these pieces:");
-
-            WriteBinItems(writer, bin);
-
-            writer.WriteLine();
-            writer.WriteLine($"  Remaining drop: {dropLength}\"");
-            writer.WriteLine();
-        }
-
-        private void WriteBinItems(StreamWriter writer, Bin bin)
-        {
-            var groups = bin.Items
-                .GroupBy(i => new { i.Name, i.Length })
-                .OrderBy(g => g.Key.Name)
-                .ThenBy(g => g.Key.Length);
-
-            var lengthHeader = "LENGTH".PadLeft(PaddingWidthOfItemLength + 1);
-            writer.WriteLine($"    QTY   {lengthHeader}   LABEL");
-
-            foreach (var group in groups)
-            {
-                var first = group.First();
-                var count = group.Count();
-                var length = FormatHelper
-                    .ConvertToMixedFraction(first.Length)
-                    .PadLeft(PaddingWidthOfItemLength) + "\"";
-
-                writer.WriteLine($"    {count,3}   {length}   {first.Name}");
-            }
-        }
-
-        private void WriteFinalSummary(StreamWriter writer)
-        {
-            var totalBars = _bins.Count();
-            var totalItems = _bins.Sum(b => b.Items.Count);
-            var totalStock = _bins.Sum(b => b.Length);
-            var totalDrop = _bins.Sum(b => b.RemainingLength);
-
-            string fmt(double v) => FormatHelper.ConvertToMixedFraction(v);
-
-            writer.WriteLine(new string('═', 50));
-            writer.WriteLine("SUMMARY");
-            writer.WriteLine($"  Stock bars needed: {totalBars}");
-            writer.WriteLine($"  Total pieces to cut: {totalItems}");
-            writer.WriteLine($"  Total material used: {fmt(totalStock)}\"");
-            writer.WriteLine($"  Total drop/waste: {fmt(totalDrop)}\"");
-            writer.WriteLine(new string('═', 50));
-        }
-
-    }
-}