feat(handler): implement default sort configuration for models

* Add SetDefaultSort method to configure default sort order
* Implement getDefaultSort method to retrieve configured defaults
* Update handleRead to apply default sort when none specified
* Add tests for default sort functionality

pkg/resolvespec/handler_test.go

@@ -41,6 +41,36 @@ func TestSetFallbackHandler(t *testing.T) {
 	}
 }
 
+func TestSetDefaultSort(t *testing.T) {
+	handler := NewHandler(nil, nil)
+
+	// No default configured yet
+	if got := handler.getDefaultSort("public", "users"); got != nil {
+		t.Errorf("Expected no default sort, got %v", got)
+	}
+
+	// Global default
+	global := []common.SortOption{{Column: "created_at", Direction: "desc"}}
+	handler.SetDefaultSort("", "", global...)
+
+	if got := handler.getDefaultSort("public", "users"); !reflect.DeepEqual(got, global) {
+		t.Errorf("Expected global default sort %v, got %v", global, got)
+	}
+
+	// Per-model default overrides the global default
+	perModel := []common.SortOption{{Column: "name", Direction: "asc"}}
+	handler.SetDefaultSort("public", "users", perModel...)
+
+	if got := handler.getDefaultSort("public", "users"); !reflect.DeepEqual(got, perModel) {
+		t.Errorf("Expected per-model default sort %v, got %v", perModel, got)
+	}
+
+	// Other models still fall back to the global default
+	if got := handler.getDefaultSort("public", "orders"); !reflect.DeepEqual(got, global) {
+		t.Errorf("Expected global default sort %v for unrelated model, got %v", global, got)
+	}
+}
+
 func TestGetDatabase(t *testing.T) {
 	handler := NewHandler(nil, nil)
 	db := handler.GetDatabase()