Adds Configuration Manager + tests

Tests/CodeSnippets/TestPostgresLISTENNOTIFY.cs

@@ -0,0 +1,43 @@
+using Npgsql;
+
+class TestPostgresLISTENNOTIFY
+{
+    static async Task Main(string[] args)
+    {
+        var connectionString = "Host=192.168.1.57;Database=ptdb01;Username=postgres;Password=3911";
+
+        try
+        {
+            await using NpgsqlConnection conn = new NpgsqlConnection(connectionString);
+            await conn.OpenAsync();
+
+            Console.WriteLine("Forbundet til databasen. Lytter efter notifikationer...");
+
+            conn.Notification += (o, e) =>
+            {
+                Console.WriteLine($"Notifikation modtaget:");
+                Console.WriteLine($"  PID: {e.PID}");
+                Console.WriteLine($"  Kanal: {e.Channel}");
+                Console.WriteLine($"  Payload: {e.Payload}");
+                Console.WriteLine("------------------------");
+            };
+
+            await using (var cmd = new NpgsqlCommand("LISTEN config_changes;", conn))
+            {
+                await cmd.ExecuteNonQueryAsync();
+            }
+
+            Console.WriteLine("Tryk på en tast for at stoppe...");
+
+            while (!Console.KeyAvailable)
+            {
+                await conn.WaitAsync();
+            }
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"Der opstod en fejl: {ex.Message}");
+            Console.WriteLine($"Stack trace: {ex.StackTrace}");
+        }
+    }
+}