refactor: modernize Go primitives

- Replace interface{} with any (Go 1.18) across confluence/api.go,
  macro/macro.go, util/cli.go, util/error_handler.go, includes/templates.go
- Replace sort.SliceStable with slices.SortStableFunc + cmp.Compare (Go 1.21)
  in attachment/attachment.go, consistent with existing slices usage
- Replace fmt.Errorf("%s", msg) with errors.New(msg) in mark.go

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

util/cli.go

@@ -23,7 +23,7 @@ func RunMark(ctx context.Context, cmd *cli.Command) error {
 	output := zerolog.ConsoleWriter{
 		Out:        os.Stderr,
 		TimeFormat: "2006-01-02 15:04:05.000",
-		FormatLevel: func(i interface{}) string {
+		FormatLevel: func(i any) string {
 			var l string
 			if ll, ok := i.(string); ok {
 				switch ll {
@@ -49,16 +49,16 @@ func RunMark(ctx context.Context, cmd *cli.Command) error {
 			}
 			return l
 		},
-		FormatFieldName: func(i interface{}) string {
+		FormatFieldName: func(i any) string {
 			return ""
 		},
-		FormatFieldValue: func(i interface{}) string {
+		FormatFieldValue: func(i any) string {
 			return fmt.Sprintf("%s", i)
 		},
-		FormatErrFieldName: func(i interface{}) string {
+		FormatErrFieldName: func(i any) string {
 			return ""
 		},
-		FormatErrFieldValue: func(i interface{}) string {
+		FormatErrFieldValue: func(i any) string {
 			return fmt.Sprintf("%s", i)
 		},
 	}