feat(viewer): migration for ViewerClassData.IsRandomLeaderSkin

Adds AddViewerClassDataIsRandomLeaderSkin migration: boolean column on
the ViewerClassData shadow table, nullable: false, defaultValue: false.
Also updates the model snapshot to reflect the new bool property.

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

SVSim.Database/Migrations/20260609212630_AddViewerClassDataIsRandomLeaderSkin.cs

@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SVSim.Database.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddViewerClassDataIsRandomLeaderSkin : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<bool>(
+                name: "IsRandomLeaderSkin",
+                table: "ViewerClassData",
+                type: "boolean",
+                nullable: false,
+                defaultValue: false);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "IsRandomLeaderSkin",
+                table: "ViewerClassData");
+        }
+    }
+}