Add server configuration service and repo

RecNet.Application/Services/Configuration/IConfigService.cs

@@ -0,0 +1,7 @@
+namespace RecNet.Application.Services.Configuration;
+
+public interface IConfigService
+{
+    Task<T?> GetAsync<T>(string key, T? defaultValue = default, CancellationToken ct = default);
+    Task SetAsync<T>(string key, T value, CancellationToken ct = default);
+}