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>

mark.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/sha1"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -97,7 +98,7 @@ func Run(config Config) error {
 		if config.CI {
 			log.Warn().Msg(msg)
 		} else {
-			return fmt.Errorf("%s", msg)
+			return errors.New(msg)
 		}
 	}