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.unlock.js

@@ -277,20 +277,9 @@ async function pinSetupFlow() {
     // Setting/changing a PIN creates a new unlock path → treat as a
     // sensitive operation. An unattended unlocked vault must not be
     // possible for a passerby to pin-backdoor.
-    const masterPwd = await askReauth(
+    const masterPwd = await reauthLoop(
         'Confirm your master password to set or change the PIN.');
     if (!masterPwd) return;
-    try {
-        const verifier = await computeVerifier(
-            masterPwd, state.salt, state.kdfIterations || 100000, state.hashAlgo, state.argon2Params);
-        await api('/reauth', {
-            method: 'POST',
-            headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({ verifier: verifier }),
-        });
-    } catch (err) {
-        return toast('Wrong master password', 'error');
-    }
 
     let lastError = '';
     let attempts = 0;
@@ -419,20 +408,9 @@ async function enableQuickUnlock() {
     if (!Bridge.active) return toast('Quick unlock requires the Delphi app', 'warning');
     if (!state.cryptoKey) return toast('Unlock the vault first', 'warning');
 
-    const masterPwd = await askReauth(
+    const masterPwd = await reauthLoop(
         'Confirm your master password to enable Quick unlock on this device.');
     if (!masterPwd) return;
-    try {
-        const verifier = await computeVerifier(
-            masterPwd, state.salt, state.kdfIterations || 100000, state.hashAlgo, state.argon2Params);
-        await api('/reauth', {
-            method: 'POST',
-            headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({ verifier: verifier }),
-        });
-    } catch (err) {
-        return toast('Wrong master password', 'error');
-    }
 
     // Export the raw key + identity. We don't store the session token —
     // tryQuickUnlock re-logs in with a verifier derived from the key,
@@ -674,7 +652,10 @@ async function unwrapAesKeyFromRecovery(wrappedKeyB64, wrappedIvB64, recoveryCod
 async function doGenerateRecoveryKey() {
     if (!state.cryptoKey) { return toast('Vault locked', 'warning'); }
 
-    const masterPwd = await askReauth(
+    // Pre-verify via reauthLoop (inline retry) so a wrong master pw re-prompts
+    // instead of failing the setup POST and closing the modal. The setup call
+    // below still carries the verifier — the server re-checks it.
+    const masterPwd = await reauthLoop(
         'Confirm your master password to generate a recovery key.');
     if (!masterPwd) return;