feat: move scheduled tasks to separate project

PluralKit.Core/Database/Migrations/19.sql

@@ -0,0 +1,10 @@
+-- schema version 19: 2021-10-15 --
+-- add stats to info table
+
+alter table info add column system_count int;
+alter table info add column member_count int;
+alter table info add column group_count int;
+alter table info add column switch_count int;
+alter table info add column message_count int;
+
+update info set schema_version = 18;

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

@@ -0,0 +1,33 @@
+using System.Threading;
+using System.Threading.Tasks;
+
+using Dapper;
+
+using SqlKata;
+
+namespace PluralKit.Core
+{
+    public partial class ModelRepository
+    {
+        public async Task UpdateStats()
+        {
+            await _db.Execute(conn => conn.ExecuteAsync("update info set system_count = (select count(*) from systems)"));
+            await _db.Execute(conn => conn.ExecuteAsync("update info set member_count = (select count(*) from members)"));
+            await _db.Execute(conn => conn.ExecuteAsync("update info set group_count = (select count(*) from groups)"));
+            await _db.Execute(conn => conn.ExecuteAsync("update info set switch_count = (select count(*) from switches)"));
+            await _db.Execute(conn => conn.ExecuteAsync("update info set message_count = (select count(*) from messages)"));
+        }
+
+        public Task<Counts> GetStats()
+            => _db.Execute(conn => conn.QuerySingleAsync<Counts>("select * from info"));
+
+        public class Counts
+        {
+            public int SystemCount { get; }
+            public int MemberCount { get; }
+            public int GroupCount { get; }
+            public int SwitchCount { get; }
+            public int MessageCount { get; }
+        }
+    }
+}

PluralKit.Core/Database/Utils/DatabaseMigrator.cs

@@ -12,7 +12,7 @@ namespace PluralKit.Core
     internal class DatabaseMigrator
     {
         private const string RootPath = "PluralKit.Core.Database"; // "resource path" root for SQL files
-        private const int TargetSchemaVersion = 18;
+        private const int TargetSchemaVersion = 19;
         private readonly ILogger _logger;
 
         public DatabaseMigrator(ILogger logger)