fix(mail): remove redundant TrimSpace in parseReferences

strings.Fields already strips whitespace from each token.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/mail/imap.go

@@ -309,9 +309,6 @@ func parseReferences(header string) []string {
 		return nil
 	}
 	raw := strings.Fields(header)
-	for i := range raw {
-		raw[i] = strings.TrimSpace(raw[i])
-	}
 	// Reverse: last (most recent) first.
 	for i, j := 0, len(raw)-1; i < j; i, j = i+1, j-1 {
 		raw[i], raw[j] = raw[j], raw[i]