feat: load application and repository configuration from env and TOML

Program.cs

@@ -0,0 +1,15 @@
+using ForgejoReleaseSync.Services;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+var builder = Host.CreateApplicationBuilder(args);
+
+var config = AppConfigLoader.LoadConfigFromEnv();
+builder.Services.AddSingleton(config);
+
+var repositoryConfig = await RepoConfigLoader.LoadConfigAsync(
+    config.RepositoryConfigFilePath);
+builder.Services.AddSingleton(repositoryConfig);
+
+var app = builder.Build();
+await app.RunAsync();