fix(reauth): wrong master pw re-prompts inline instead of closing

Setting a PIN, enabling Quick Unlock, and generating a recovery key all
closed the reauth modal and showed a toast on the first wrong master
password — no retry. Export already looped inline; the others didn't.

Extracted that loop into reauthLoop(message): re-prompts with an inline
error + attempt count (5 tries), honours the 429 lockout, returns the
verified password or null. All four sensitive-action flows now share it, so
a mistyped master password keeps the modal up to try again.

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

js/app.js

@@ -6022,6 +6022,45 @@ function closeReauth(ok) {
     }
 }
 
+// Prompt for the master password and verify it via /reauth, RE-PROMPTING
+// inline on a wrong entry (the modal stays up with an error + attempt count)
+// instead of closing on the first miss. The single choke point for every
+// sensitive-action reauth (export, PIN set, Quick Unlock, recovery) so they
+// all behave the same. Returns the verified master password, or null when the
+// user cancels or the attempt cap / server lockout is hit (already toasted).
+async function reauthLoop(message) {
+    const MAX = 5;
+    let attempts = 0;
+    let lastError = '';
+    for (;;) {
+        const pwd = await askReauth(message, { error: lastError });
+        if (!pwd) return null;   // cancelled
+        try {
+            const verifier = await computeVerifier(
+                pwd, state.salt, state.kdfIterations || 100000,
+                state.hashAlgo, state.argon2Params);
+            await api('/reauth', {
+                method: 'POST',
+                headers: authHeaders({ 'Content-Type': 'application/json' }),
+                body: JSON.stringify({ verifier }),
+            });
+            return pwd;
+        } catch (err) {
+            if (err.status === 429 && err.body && err.body.retry_after) {
+                toast('Account locked. Try again in ' +
+                    Math.ceil(err.body.retry_after / 60) + ' min', 'warning');
+                return null;
+            }
+            attempts++;
+            if (attempts >= MAX) {
+                toast('Too many wrong attempts — try again later', 'error');
+                return null;
+            }
+            lastError = 'Wrong master password. Attempt ' + attempts + ' / ' + MAX + '.';
+        }
+    }
+}
+
 // ============================================================
 // QUICK UNLOCK + PIN + RECOVERY KEY — extracted to js/app.unlock.js (§3.1),
 // loaded AFTER this file (it assigns Bridge.onQuickUnlockResult / onPinResult