skip zxcvbn strength check for passwords 50+ chars to eliminate UI lag on long password generation (v5.1.4)

@@ -155,6 +155,11 @@155155   createEffect(async () => {156156     const pwd = password();157157     if (pwd.length < 4) { setPasswordStrength(null); return; }158+    // zxcvbn does full dictionary + spatial + repeat analysis across every159+    // character, so a 100+ char password blocks the main thread for hundreds160+    // of ms per slider tick. Any 50+ char password is trivially score 4 —161+    // skip the analysis and keep the slider responsive.162+    if (pwd.length >= 50) { setPasswordStrength(4); return; }158163     try {159164       if (!zxcvbnFn()) {160165         // Replaces the unmaintained `zxcvbn` package (LV-8; see Lock.tsx).