fix: repair double-encoded degree symbol in DXF output

ACadSharp misreads UTF-8 degree symbol (C2 B0) as two ANSI_1252
characters (°) then writes that back out. Post-process the saved
DXF to replace ° with ° so bend notes display correctly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

EtchBendLines/Etcher.cs

@@ -86,9 +86,22 @@ namespace EtchBendLines
             {
                 writer.Write();
             }
+
+            FixDegreeSymbol(path);
+
             Console.WriteLine($"→ Saved with etch lines: {path}");
         }
 
+        private static void FixDegreeSymbol(string path)
+        {
+            var text = File.ReadAllText(path);
+            if (text.Contains("\u00C2\u00B0"))
+            {
+                text = text.Replace("\u00C2\u00B0", "\u00B0");
+                File.WriteAllText(path, text);
+            }
+        }
+
         private static string KeyFor(Line l) => KeyFor(l.StartPoint, l.EndPoint);
 
         private static string KeyFor(XYZ a, XYZ b) => $"{a.X:F3},{a.Y:F3}|{b.X:F3},{b.Y:F3}";