feat(slideover): per-entry password strength bar

The entry modal + register already show a strength bar; the slideover
password field didn't. Added one in soPasswordField reusing the existing
.strength-bar/--strength CSS and computeStrength (no zxcvbn). Vault health
already scores weakness via the same function.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

js/app.js

@@ -4364,6 +4364,13 @@ function soPasswordField(plain) {
     row.appendChild(copy);
     row.appendChild(gen);
     wrap.appendChild(row);
+    // Live strength bar — same .strength-bar/--strength pattern as the entry
+    // modal + register, reusing computeStrength (no zxcvbn).
+    const bar = el('div', { class: 'strength-bar', id: 'soStrengthBar' });
+    const setStr = () => bar.style.setProperty('--strength', computeStrength(input.value) + '%');
+    input.addEventListener('input', setStr);
+    setStr();
+    wrap.appendChild(bar);
     return wrap;
 }