Implement BossPvP logic (I implemented this based on undownding's code. Thank you!)

Common/Data/Excel/BossPvpBossChallengeExcel.cs

@@ -0,0 +1,32 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using System.Globalization;
+
+namespace MikuSB.Data.Excel;
+
+[ResourceEntity("challenge/bosspvp/boss_challenge.json")]
+public class BossPvpBossChallengeExcel : ExcelResource
+{
+    public uint ID { get; set; }
+    public string StartTime { get; set; } = "";
+    public string EndTime { get; set; } = "";
+    public List<uint> tbTaskID { get; set; } = [];
+
+    [JsonExtensionData] public IDictionary<string, JToken> ExtraData { get; set; } = new Dictionary<string, JToken>();
+
+    [JsonIgnore] public List<uint> BossIds { get; private set; } = [];
+
+    public override uint GetId() => ID;
+
+    public override void Loaded()
+    {
+        BossIds = ExtraData
+            .Where(x => x.Key.StartsWith("Boss", StringComparison.Ordinal) && int.TryParse(x.Key[4..], out _))
+            .OrderBy(x => int.Parse(x.Key[4..], CultureInfo.InvariantCulture))
+            .Select(x => x.Value.Type == JTokenType.Integer ? x.Value.Value<uint>() : 0u)
+            .Where(x => x > 0)
+            .ToList();
+
+        GameData.BossPvpBossChallengeData[ID] = this;
+    }
+}