fix: cast hid parameter to char(6) in GetMemberByHid query

avoids casting the hid column, which does a full table scan, which is slow

Myriad/Rest/BaseRestClient.cs

@@ -35,7 +35,10 @@ public class BaseRestClient: IAsyncDisposable
         if (!token.StartsWith("Bot "))
             token = "Bot " + token;
 
-        Client = new HttpClient();
+        Client = new HttpClient(new SocketsHttpHandler
+        {
+            PooledConnectionIdleTimeout = TimeSpan.FromSeconds(3),
+        });
         Client.DefaultRequestHeaders.TryAddWithoutValidation("User-Agent", userAgent);
         Client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", token);
 

PluralKit.Core/Database/Repository/ModelRepository.Member.cs

@@ -13,7 +13,7 @@ public partial class ModelRepository
 
     public Task<PKMember?> GetMemberByHid(string hid, SystemId? system = null)
     {
-        var query = new Query("members").Where("hid", hid.ToLower());
+        var query = new Query("members").WhereRaw("hid = (?)::char(6)", hid.ToLower());
         if (system != null)
             query = query.Where("system", system);
         return _db.QueryFirst<PKMember?>(query);