feat(server): record set releases and the nests they made

Releasing a drawing set makes one nest per material group, so a kit run
spans several nests. The server now records which set revision was
released, the multiplier and the nests it made, so a run can be tracked
across its nests and a nest can say where it came from.

The client uploads every nest first and posts the release last: a failure
part-way leaves ordinary nests and no release, never a release pointing at
missing nests. For the same reason a release is accepted for an older set
revision or an archived set, since the nests already exist by then. The
release id is client-allocated and a nest belongs to at most one release,
so a retried post gets 409 with the release that already holds it.

Releases are append-only and read joined to each nest's current metadata,
so status and deletion are always current. The tables join schema v7, as
the set tables have not shipped yet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest.Data/SetReleasePage.cs

@@ -0,0 +1,14 @@
+namespace OpenNest.Data;
+
+/// <summary>One bounded page of set releases, newest first, each with its nests.</summary>
+public sealed class SetReleasePage
+{
+    public IReadOnlyList<SetReleaseRecord> Items { get; init; } = Array.Empty<SetReleaseRecord>();
+
+    /// <summary>Number of releases of the set across all pages.</summary>
+    public int Total { get; init; }
+
+    public int Offset { get; init; }
+
+    public int Limit { get; init; }
+}