Added package filtering

sh.actions.package-cleanup/ConfigurationExtension.cs

@@ -0,0 +1,26 @@
+namespace sh.actions.package_cleanup;
+
+public static class ConfigurationExtension
+{
+    private static void EnsureVariable(IConfiguration configuration, string key)
+    {
+        var value = configuration[key];
+        if (string.IsNullOrEmpty(value))
+        {
+            throw new InvalidOperationException($"Configuration variable '{key}' is required but was not found.");
+        }
+    }
+
+    public static IConfigurationBuilder EnsureGiteaConfig(this IConfigurationBuilder builder)
+    {
+        var configuration = builder.Build();
+
+        EnsureVariable(configuration, "URL");
+        EnsureVariable(configuration, "OWNER");
+        EnsureVariable(configuration, "TYPE");
+        EnsureVariable(configuration, "NAME");
+        EnsureVariable(configuration, "API_TOKEN");
+
+        return builder;
+    }
+}