feat(pwa): add install prompt banner and register in all POS templates

- pwa-install.js: captures beforeinstallprompt, shows dismissible
  banner with 7-day localStorage cooldown, handles appinstalled
- Registered in 12 POS templates alongside existing service worker

pos/static/js/pwa-install.js

@@ -0,0 +1,101 @@
+/**
+ * Nexus POS — PWA Install Prompt
+ * Captures beforeinstallprompt and shows a dismissible banner.
+ */
+(function () {
+  'use strict';
+
+  const STORAGE_KEY = 'nexus_pwa_install_dismissed';
+  let deferredPrompt = null;
+
+  function createBanner() {
+    if (document.getElementById('pwa-install-banner')) return;
+
+    const banner = document.createElement('div');
+    banner.id = 'pwa-install-banner';
+    banner.innerHTML = `
+      <span>📲 Instala Nexus POS para acceso rápido y modo offline.</span>
+      <button id="pwa-install-btn">Instalar</button>
+      <button id="pwa-dismiss-btn" aria-label="Cerrar">&times;</button>
+    `;
+    document.body.appendChild(banner);
+
+    const style = document.createElement('style');
+    style.textContent = `
+      #pwa-install-banner {
+        position: fixed;
+        bottom: 0; left: 0; right: 0;
+        background: var(--color-surface, #1a1a1a);
+        color: var(--color-text, #eee);
+        border-top: 1px solid var(--color-border, #333);
+        padding: 12px 16px;
+        display: flex;
+        align-items: center;
+        gap: 12px;
+        font-size: 14px;
+        z-index: 9999;
+        box-shadow: 0 -4px 12px rgba(0,0,0,0.3);
+      }
+      #pwa-install-banner span { flex: 1; }
+      #pwa-install-btn {
+        background: var(--color-primary, #F5A623);
+        color: #000;
+        border: none;
+        padding: 8px 16px;
+        border-radius: 6px;
+        font-weight: 600;
+        cursor: pointer;
+      }
+      #pwa-dismiss-btn {
+        background: none;
+        border: none;
+        color: var(--color-text-muted, #888);
+        font-size: 20px;
+        cursor: pointer;
+        line-height: 1;
+      }
+    `;
+    document.head.appendChild(style);
+
+    document.getElementById('pwa-install-btn').addEventListener('click', function () {
+      if (!deferredPrompt) return;
+      deferredPrompt.prompt();
+      deferredPrompt.userChoice.then(function (choice) {
+        if (choice.outcome === 'accepted') {
+          console.log('[PWA] User accepted install');
+        }
+        deferredPrompt = null;
+        banner.remove();
+      });
+    });
+
+    document.getElementById('pwa-dismiss-btn').addEventListener('click', function () {
+      localStorage.setItem(STORAGE_KEY, Date.now().toString());
+      banner.remove();
+    });
+  }
+
+  window.addEventListener('beforeinstallprompt', function (e) {
+    e.preventDefault();
+    deferredPrompt = e;
+
+    const dismissed = localStorage.getItem(STORAGE_KEY);
+    if (dismissed && (Date.now() - parseInt(dismissed)) < 7 * 24 * 60 * 60 * 1000) {
+      return; // dismissed within 7 days
+    }
+
+    // Wait for DOM to be ready
+    if (document.readyState === 'loading') {
+      document.addEventListener('DOMContentLoaded', createBanner);
+    } else {
+      createBanner();
+    }
+  });
+
+  window.addEventListener('appinstalled', function () {
+    console.log('[PWA] App installed');
+    deferredPrompt = null;
+    const b = document.getElementById('pwa-install-banner');
+    if (b) b.remove();
+  });
+})();

pos/templates/accounting.html

@@ -495,6 +495,7 @@
   <script src="/pos/static/js/accounting.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>

pos/templates/catalog.html

@@ -279,5 +279,6 @@
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script src="/pos/static/js/onboarding.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 </body>
 </html>

pos/templates/config.html

@@ -688,6 +688,7 @@
   <script src="/pos/static/js/config.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>

pos/templates/customers.html

@@ -624,6 +624,7 @@
   <script src="/pos/static/js/offline-banner.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
   <script src="/pos/static/js/chat.js" defer></script>
 </body>
 </html>

pos/templates/dashboard.html

@@ -352,6 +352,33 @@
           </div><!-- end chart-card -->
         </section>
 
+        <!-- =================================================================
+             ESTADÍSTICAS EN TIEMPO REAL
+             ================================================================= -->
+        <section>
+          <div class="section-header">
+            <span class="section-title">Rendimiento Hoy</span>
+          </div>
+          <div class="two-col-grid">
+            <div class="rank-card">
+              <div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-4);">
+                <div style="font-family:var(--font-heading);font-weight:var(--heading-weight-secondary);font-size:var(--text-body-sm);letter-spacing:var(--tracking-wider);text-transform:uppercase;color:var(--color-text-secondary);">
+                  Ventas por Hora
+                </div>
+              </div>
+              <canvas id="hourlySalesChart" height="180"></canvas>
+            </div>
+            <div class="rank-card">
+              <div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-4);">
+                <div style="font-family:var(--font-heading);font-weight:var(--heading-weight-secondary);font-size:var(--text-body-sm);letter-spacing:var(--tracking-wider);text-transform:uppercase;color:var(--color-text-secondary);">
+                  Top Productos (Hoy)
+                </div>
+              </div>
+              <canvas id="topProductsChart" height="180"></canvas>
+            </div>
+          </div>
+        </section>
+
         <!-- =================================================================
              TOP PRODUCTOS / TOP CLIENTES
              ================================================================= -->
@@ -453,13 +480,16 @@
   </div><!-- end app-shell -->
 
 
+  <script src="/pos/static/js/chart.umd.min.js" defer></script>
   <script src="/pos/static/js/i18n.js" defer></script>
   <script src="/pos/static/js/app-init.js" defer></script>
   <script src="/pos/static/js/pos-utils.js" defer></script>
   <script src="/pos/static/js/sidebar.js" defer></script>
+  <script src="/pos/static/js/dashboard-stats.js" defer></script>
   <script src="/pos/static/js/dashboard.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>

pos/templates/diagrams.html

@@ -154,6 +154,7 @@
   <script src="/pos/static/js/sidebar.js" defer></script>
   <script src="/pos/static/js/diagrams.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
   <script src="/pos/static/js/chat.js" defer></script>
 </body>
 </html>

pos/templates/fleet.html

@@ -308,6 +308,7 @@
 <script src="/pos/static/js/fleet.js" defer></script>
 <script src="/pos/static/js/offline-banner.js" defer></script>
 <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>

pos/templates/inventory.html

@@ -819,6 +819,7 @@
   <script src="/pos/static/js/offline-banner.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
   <script src="/pos/static/js/chat.js" defer></script>
 </body>
 </html>

pos/templates/invoicing.html

@@ -1057,6 +1057,7 @@
   <script src="/pos/static/js/invoicing.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>

pos/templates/login.html

@@ -532,6 +532,7 @@
   <script src="/pos/static/js/kiosk.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
 </body>
 </html>

pos/templates/pos.html

@@ -560,5 +560,6 @@
   <script src="/pos/static/js/chat.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 </body>
 </html>

pos/templates/reports.html

@@ -323,6 +323,7 @@
   <script src="/pos/static/js/reports.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
+  <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
 </body>