feat(verifactu): persist certificate token in localStorage

- Add saveVeriFactuToken / getVeriFactuToken / clearVeriFactuToken helpers in verifactu.js
- Save token to localStorage (key: verifactu_cert_token) after successful registration
- Show active token status on SettingsPage load (first 8 chars + ellipsis)
- Add "Borrar token" button that appears only when a token is stored

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/SettingsPage.js

@@ -2,7 +2,7 @@ import { isDarkTheme, toggleTheme } from '../services/theme.js';
 import { icons } from '../services/icons.js';
 import { apiGet, apiPut } from '../services/apiClient.js';
 import { showToast } from '../services/toast.js';
-import { encryptVeriFactuPassword, formatVeriFactuError, getVeriFactuFormats, getVeriFactuHealth, registerVeriFactuCertificate } from '../services/verifactu.js';
+import { encryptVeriFactuPassword, formatVeriFactuError, getVeriFactuFormats, getVeriFactuHealth, registerVeriFactuCertificate, saveVeriFactuToken, getVeriFactuToken, clearVeriFactuToken } from '../services/verifactu.js';
 
 function decodeTokenPayload(token) {
   try {
@@ -155,6 +155,7 @@ export function renderSettingsPage() {
           <div style="display:flex;gap:0.75rem;justify-content:flex-end;flex-wrap:wrap">
             <button type="button" class="btn-cancel-compact" id="verifactu-health-btn">Comprobar API</button>
             <button type="button" class="btn-cancel-compact" id="verifactu-formats-btn">Ver formatos</button>
+            <button type="button" class="btn-cancel-compact" id="verifactu-clear-token-btn" style="display:none">Borrar token</button>
             <button type="button" class="btn-submit-compact" id="verifactu-register-btn">Registrar certificado</button>
           </div>
           <p id="verifactu-status" style="font-size:0.8rem;color:var(--text-secondary);min-height:1.2em"></p>
@@ -202,6 +203,26 @@ export function renderSettingsPage() {
   const verifactuCertName = container.querySelector('#verifactu-cert-name');
   const verifactuCertFile = container.querySelector('#verifactu-cert-file');
   const verifactuCertPassword = container.querySelector('#verifactu-cert-password');
+  const clearTokenBtn = container.querySelector('#verifactu-clear-token-btn');
+
+  const renderVeriFactuTokenStatus = () => {
+    const token = getVeriFactuToken();
+    if (token) {
+      verifactuStatus.textContent = `Token activo: ${token.slice(0, 8)}...`;
+      clearTokenBtn.style.display = '';
+    } else {
+      clearTokenBtn.style.display = 'none';
+    }
+  };
+
+  renderVeriFactuTokenStatus();
+
+  clearTokenBtn.addEventListener('click', () => {
+    clearVeriFactuToken();
+    verifactuStatus.textContent = 'Token eliminado.';
+    clearTokenBtn.style.display = 'none';
+    showToast('Token de VeriFactu eliminado', 'success');
+  });
 
   verifactuCertFile.addEventListener('change', () => {
     const file = verifactuCertFile.files?.[0];
@@ -333,8 +354,12 @@ export function renderSettingsPage() {
         return;
       }
 
-      const token = result.token ? ` Token: ${result.token}` : '';
-      verifactuStatus.textContent = `Certificado registrado.${token}`;
+      if (result.token) {
+        saveVeriFactuToken(result.token);
+        renderVeriFactuTokenStatus();
+      }
+      const tokenHint = result.token ? ` Token: ${result.token.slice(0, 8)}...` : '';
+      verifactuStatus.textContent = `Certificado registrado.${tokenHint}`;
       showToast('Certificado registrado en VeriFactu', 'success');
     } catch (error) {
       const errorMessage = formatVeriFactuError(error);

src/services/verifactu.js

@@ -3,6 +3,22 @@ import { apiGet, apiPost } from './apiClient.js';
 
 let cachedPublicKeyPem = null;
 
+const VERIFACTU_TOKEN_KEY = 'verifactu_cert_token';
+
+export function saveVeriFactuToken(token) {
+  if (token) {
+    localStorage.setItem(VERIFACTU_TOKEN_KEY, token);
+  }
+}
+
+export function getVeriFactuToken() {
+  return localStorage.getItem(VERIFACTU_TOKEN_KEY) || null;
+}
+
+export function clearVeriFactuToken() {
+  localStorage.removeItem(VERIFACTU_TOKEN_KEY);
+}
+
 const VERIFACTU_ERROR_MESSAGES = {
   missing_fields: 'Faltan campos obligatorios para registrar el certificado.',
   invalid_json: 'La peticion enviada a VeriFactu no tiene un JSON valido.',