refactor(urltools): Make regular expression static

domainHasIllegalCharacters() constructs a QRegularExpression on every call.
Since the pattern is constant, make it static const QRegularExpression
  to avoid repeated regex compilation in hot paths
  (e.g., domain validation during browsing/passkey operations).

Author: aollier

src/gui/UrlTools.cpp

@@ -211,6 +211,6 @@ bool UrlTools::isUrlValid(const QString& urlField, bool looseComparison)
 
 bool UrlTools::domainHasIllegalCharacters(const QString& domain)
 {
-    const QRegularExpression re(R"([\s\^#|/:<>\?@\[\]\\])");
+    static const QRegularExpression re(R"([\s\^#|/:<>\?@\[\]\\])");
     return re.match(domain).hasMatch();
 }