added ServerConfigurationMapping

split up Abstractions so we have one type per file.

pgLabII.PgUtils/ConnectionStrings/ConnectionDescriptor.cs

@@ -0,0 +1,29 @@
+using Npgsql;
+
+namespace pgLabII.PgUtils.ConnectionStrings;
+
+/// <summary>
+/// Canonical, format-agnostic representation of a PostgreSQL connection.
+/// Keep minimal fields for broad interoperability; store extras in Properties.
+/// </summary>
+public sealed class ConnectionDescriptor
+{
+    public string? Name { get; init; }
+
+    // Primary hosts (support multi-host). If empty, implies localhost default.
+    public IReadOnlyList<HostEndpoint> Hosts { get; init; } = new List<HostEndpoint>();
+
+    public string? Database { get; init; }
+    public string? Username { get; init; }
+    public string? Password { get; init; }
+
+    public SslMode? SslMode { get; init; }
+
+    // Common optional fields
+    public string? ApplicationName { get; init; }
+    public int? TimeoutSeconds { get; init; } // connect_timeout
+
+    // Additional parameters preserved across conversions
+    public IReadOnlyDictionary<string, string> Properties { get; init; } =
+        new Dictionary<string, string>();
+}