feat(core,io): persist nest status and made-by in nest files

Add NestStatus (Quote/ToBeCut/HasBeenCut) plus MadeBy on Nest, written as
additive camelCase nest.json fields with PascalCase enum strings matching
the units convention. Legacy files and unknown status values fall back to
Quote. The nest info dialog gains a Status dropdown and Made By box.

OpenNest.IO/NestReader.cs

@@ -341,6 +341,11 @@ namespace OpenNest.IO
             nest.DateLastModified = DateTime.Parse(dto.DateLastModified);
             nest.Notes = dto.Notes;
             nest.AssistGas = dto.AssistGas ?? "";
+            // Additive v2 fields: absent or unknown values keep the defaults.
+            nest.Status = Enum.TryParse<NestStatus>(dto.Status, true, out var status)
+                ? status
+                : NestStatus.Quote;
+            nest.MadeBy = dto.MadeBy ?? "";
 
             // Nest-level material and thickness (fall back to PlateDefaults for old files)
             var pd = dto.PlateDefaults;