Deserialize activity party size as string array with on-demand parsing (#140)

* Initial plan

* Deserialize party size as string array and convert on-demand with overflow handling

Co-authored-by: Quahu <24848652+Quahu@users.noreply.github.com>

* Rename ParseInt to ParseSizeInt and remove self-explanatory comments

Co-authored-by: Quahu <24848652+Quahu@users.noreply.github.com>

---------

Co-authored-by: anthropic-code-agent[bot] <242468646+Claude@users.noreply.github.com>
Co-authored-by: Quahu <24848652+Quahu@users.noreply.github.com>

Author: Claude

src/Disqord.Gateway.Api/Models/Activity/ActivityPartyJsonModel.cs

@@ -9,5 +9,5 @@ public class ActivityPartyJsonModel : JsonModel
     public Optional<string> Id;
 
     [JsonProperty("size")]
-    public Optional<int[]> Size;
+    public Optional<string[]> Size;
 }

src/Disqord.Gateway/Entities/Transient/Guild/Presence/Activity/Rich/TransientRichActivityParty.cs

@@ -1,4 +1,5 @@
-using Disqord.Gateway.Api.Models;
+using System;
+using Disqord.Gateway.Api.Models;
 using Qommon;
 
 namespace Disqord.Gateway;
@@ -9,12 +10,42 @@ public class TransientRichActivityParty : TransientEntity<ActivityPartyJsonModel
     public string? Id => Model.Id.GetValueOrDefault();
 
     /// <inheritdoc/>
-    public int? Size => Model.Size.GetValueOrDefault()?[0];
+    public int? Size => ParseSizeInt(Model.Size.GetValueOrDefault(), 0);
 
     /// <inheritdoc/>
-    public int? MaximumSize => Model.Size.GetValueOrDefault()?[1];
+    public int? MaximumSize => ParseSizeInt(Model.Size.GetValueOrDefault(), 1);
 
     public TransientRichActivityParty(ActivityPartyJsonModel model)
         : base(model)
     { }
+
+    private static int? ParseSizeInt(string[]? array, int index)
+    {
+        if (array == null || index >= array.Length)
+            return null;
+
+        var stringValue = array[index];
+        if (string.IsNullOrEmpty(stringValue))
+            return null;
+
+        if (long.TryParse(stringValue, out var longValue))
+        {
+            if (longValue > int.MaxValue)
+                return int.MaxValue;
+            if (longValue < int.MinValue)
+                return int.MinValue;
+            return (int)longValue;
+        }
+
+        if (double.TryParse(stringValue, out var doubleValue))
+        {
+            if (doubleValue > int.MaxValue)
+                return int.MaxValue;
+            if (doubleValue < int.MinValue)
+                return int.MinValue;
+            return (int)doubleValue;
+        }
+
+        return null;
+    }
 }