feat(missions): add 3 catalog entities (mission, achievement, BP monthly)

SVSim.Database/Models/BattlePassMonthlyMissionEntry.cs

@@ -0,0 +1,28 @@
+using System.ComponentModel.DataAnnotations.Schema;
+using SVSim.Database.Common;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One row of the BP monthly mission list, keyed to a specific (Year, Month).
+/// `RewardType` is nullable because some monthly missions only award BP points (capture shows
+/// the "Play 5 Challenge matches" entry has no reward_info block on wire).
+/// Id is auto-generated — override BaseEntity's [DatabaseGenerated(None)] default.
+/// </summary>
+public class BattlePassMonthlyMissionEntry : BaseEntity<int>
+{
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    public override int Id { get; set; }
+
+    public int Year { get; set; }
+    public int Month { get; set; }
+    public int OrderNum { get; set; }
+    public string Name { get; set; } = "";
+    public int RequireNumber { get; set; }
+    public int BattlePassPoint { get; set; }
+    public int? RewardType { get; set; }
+    public long? RewardDetailId { get; set; }
+    public int? RewardNumber { get; set; }
+    public string? EventType { get; set; }
+    public int? EventArg { get; set; }
+}