feat: import/export settings, send backup of settings when leaving guild

Catalogger.Backend/Database/Repositories/GuildRepository.cs

@@ -137,6 +137,23 @@ public class GuildRepository(ILogger logger, DatabaseConnection conn)
             new { Id = id.Value, Channels = config }
         );
 
+    public async Task ImportConfigAsync(
+        ulong id,
+        Guild.ChannelConfig channels,
+        string[] bannedSystems,
+        ulong[] keyRoles
+    ) =>
+        await conn.ExecuteAsync(
+            "update guilds set channels = @channels::jsonb, banned_systems = @bannedSystems, key_roles = @keyRoles where id = @id",
+            new
+            {
+                id,
+                channels,
+                bannedSystems,
+                keyRoles,
+            }
+        );
+
     public void Dispose()
     {
         conn.Dispose();