feat(data): storage-mode settings and remote nest repository

NestStorageSettings persists the file/database toggle and server URL at
%APPDATA%\OpenNest\storage.json following the EngineSelectionSettings
never-throwing pattern; missing config means File mode. NestRecord carries
the shareable job metadata, INestRepository defines the backend contract,
and RemoteNestRepository implements it against the nest server with
multipart uploads (metadata JSON part + .nest file part).

OpenNest.Data/NestRecord.cs

@@ -0,0 +1,42 @@
+using OpenNest;
+
+namespace OpenNest.Data;
+
+/// <summary>
+/// Server-side metadata for one saved nest. The .nest archive itself is stored
+/// alongside; this record is what lists, filters and status tracking read.
+/// Counts are captured by the client at save time.
+/// </summary>
+public sealed class NestRecord
+{
+    public Guid Id { get; set; }
+
+    public string Name { get; set; } = "";
+
+    public string Customer { get; set; } = "";
+
+    public DateTime DateCreated { get; set; }
+
+    public DateTime DateModified { get; set; }
+
+    public string Material { get; set; } = "";
+
+    public double Thickness { get; set; }
+
+    /// <summary>quote | toBeCut | hasBeenCut (camelCase on the wire, case-insensitive readers).</summary>
+    public NestStatus Status { get; set; } = NestStatus.Quote;
+
+    public int PlateCount { get; set; }
+
+    public int PartCount { get; set; }
+
+    public string Comments { get; set; } = "";
+
+    public string MadeBy { get; set; } = "";
+
+    /// <summary>Size of the stored .nest archive in bytes.</summary>
+    public long FileSize { get; set; }
+
+    /// <summary>When the server last stored the nest contents or metadata.</summary>
+    public DateTime SavedAt { get; set; }
+}