feat: complete session — catalog, marketplace, WhatsApp, peer-to-peer, install scripts

Major features:
- Pixel-Perfect glassmorphism design (landing + POS + public catalog)
- OEM/Local catalog toggle with Nexpart taxonomy (14 groups, 108 subgroups, 558 part types)
- Marketplace B2B Phase 1 (bodegas, POs, status machine, WA+email notifications)
- Peer-to-peer inventory (multi-instance, LAN discovery)
- WhatsApp: photo→Vision AI, voice→Whisper, conversational quotations
- Smart unified search (VIN/plate/part_number/keyword auto-detect)
- Shop Supplies tab (vehicle-independent parts)
- Chatbot AI fallback chain (5 models) + response cache
- CSV inventory import tool + setup_instance.sh installer
- Tablet-responsive CSS + sidebar toggle
- Filters, export CSV, employee edit, business data save
- Quotation system (WA→POS) with auto-print on confirmation
- Live stats on landing page

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pos/templates/whatsapp.html

@@ -6,6 +6,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
   <title>WhatsApp — Nexus Autoparts POS</title>
   <link rel="stylesheet" href="/pos/static/css/tokens.css" />
+  <link rel="stylesheet" href="/pos/static/css/pos-glass.css" />
   <link rel="manifest" href="/pos/static/pwa/manifest.json" />
   <meta name="theme-color" content="#F5A623" />
 
@@ -200,6 +201,24 @@
       margin-top: 2px;
     }
 
+    .conv-item__delete {
+      position: absolute;
+      top: 8px;
+      right: 8px;
+      background: none;
+      border: none;
+      color: var(--color-text-muted);
+      font-size: 16px;
+      cursor: pointer;
+      opacity: 0;
+      transition: opacity 0.15s;
+      padding: 2px 6px;
+      border-radius: 4px;
+    }
+    .conv-item:hover .conv-item__delete { opacity: 1; }
+    .conv-item__delete:hover { color: #F85149; background: rgba(248,81,73,0.1); }
+    .conv-item { position: relative; }
+
     .conv-empty {
       padding: var(--space-6);
       text-align: center;
@@ -611,7 +630,8 @@ function posLogout(){localStorage.removeItem('pos_token');window.location.href='
 <!-- Sidebar -->
 <script src="/pos/static/js/i18n.js"></script>
 <script src="/pos/static/js/whatsapp.js"></script>
-<script src="/pos/static/js/sidebar.js"></script>
+<script src="/pos/static/js/pos-utils.js"></script>
+  <script src="/pos/static/js/sidebar.js"></script>
 
 </body>
 </html>