feat(home-dialog): add HomeDialogEntry entity + migration

DDL-only per migrations-are-ddl-only convention. Seeded by
SVSim.Bootstrap MyPageGlobalsImporter (T5) — no HasData.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.Database/Models/HomeDialogEntry.cs

@@ -0,0 +1,31 @@
+using System.ComponentModel.DataAnnotations.Schema;
+using SVSim.Database.Common;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One mypage home-dialog popup from /mypage/index data.home_dialog_list. Id is authored in
+/// the seed file (no stable wire ID; see banners.json for the same pattern). The dialog fires
+/// once per viewer per server-process lifetime — see IHomeDialogSessionTracker.
+/// </summary>
+public class HomeDialogEntry : BaseEntity<int>
+{
+    public string TitleTextId { get; set; } = string.Empty;
+    public string Image { get; set; } = string.Empty;
+
+    /// <summary>jsonb — List&lt;HomeDialogButtonSeed&gt; serialized verbatim. Deserialized in
+    /// MyPageController via JsonbReadOptions.</summary>
+    [Column(TypeName = "jsonb")]
+    public string ButtonListJson { get; set; } = "[]";
+
+    public DateTime BeginTime { get; set; }
+    public DateTime EndTime { get; set; }
+
+    /// <summary>Wire "type" — client parser ignores it but prod sends "1". Nullable so we
+    /// omit when unset; serialized as a string per <c>HomeDialog.Type</c> on the DTO.</summary>
+    public int? Type { get; set; }
+
+    /// <summary>Tiebreaker when multiple entries are active. Higher wins; ID asc breaks
+    /// further ties. Each /mypage/index call emits the highest-priority unfired entry.</summary>
+    public int Priority { get; set; }
+}