feat(pos/chat): add 4 AI chatbot improvements — symptom diagnosis, smart quotes, photo ID, multilanguage

1. Symptom diagnosis: AI now detects vehicle symptoms and suggests probable parts
2. Smart quotations: "cotizame frenos completos" returns multiple search_queries (pipe-separated), backend searches each term and deduplicates
3. Photo identification: camera button in chat widget uploads image and sends placeholder prompt (ready for vision model)
4. Multilanguage: AI detects user language and responds accordingly, search_query always in English

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

pos/static/js/chat.js

@@ -39,6 +39,8 @@
       </div>
       <div class="chat-input-area">
         <textarea class="chat-input" id="chatInput" placeholder="Ej: Balatas para Tsuru 2015..." rows="1"></textarea>
+        <input type="file" id="chatImageInput" accept="image/*" capture="environment" style="display:none;">
+        <button class="chat-cam-btn" id="chatCam" aria-label="Enviar foto de parte" title="Identificar parte por foto">&#128247;</button>
         ${hasSpeechAPI ? '<button class="chat-mic-btn" id="chatMic" aria-label="Entrada por voz" title="Entrada por voz">&#127908;</button>' : ''}
         <button class="chat-send-btn" id="chatSend" aria-label="Enviar">&#9654;</button>
       </div>
@@ -58,6 +60,12 @@
       }
     });
 
+    // Camera button — identify part by photo
+    document.getElementById('chatCam').addEventListener('click', function () {
+      document.getElementById('chatImageInput').click();
+    });
+    document.getElementById('chatImageInput').addEventListener('change', handleImageUpload);
+
     // Mic button (only if Speech API available)
     if (hasSpeechAPI) {
       document.getElementById('chatMic').addEventListener('click', toggleVoice);
@@ -162,6 +170,82 @@
     }, 2000);
   }
 
+  // ─── Image Upload (Part identification placeholder) ───
+  function handleImageUpload(e) {
+    const file = e.target.files && e.target.files[0];
+    if (!file) return;
+
+    // Reset input so the same file can be selected again
+    e.target.value = '';
+
+    // Validate file type and size (max 5MB)
+    if (!file.type.startsWith('image/')) {
+      addBubble('Solo se permiten imagenes.', 'ai');
+      return;
+    }
+    if (file.size > 5 * 1024 * 1024) {
+      addBubble('La imagen es muy grande (max 5MB).', 'ai');
+      return;
+    }
+
+    // Show image thumbnail in chat
+    const reader = new FileReader();
+    reader.onload = function (ev) {
+      const container = document.getElementById('chatMessages');
+      const typing = document.getElementById('chatTyping');
+      const div = document.createElement('div');
+      div.className = 'chat-msg user chat-msg-image';
+      div.innerHTML = '<img src="' + ev.target.result + '" alt="Foto de parte" style="max-width:180px;max-height:140px;border-radius:8px;display:block;margin-bottom:4px;">'
+        + '<span>Identificar esta parte</span>';
+      container.insertBefore(div, typing);
+      scrollToBottom();
+
+      // Send to AI as a text description (vision model placeholder)
+      const photoPrompt = 'El usuario envio una foto de una parte automotriz. Describe que parte podria ser y sugiere busquedas.';
+      history.push({ role: 'user', content: photoPrompt });
+      if (history.length > 20) history.splice(0, 2);
+
+      isSending = true;
+      document.getElementById('chatSend').disabled = true;
+      showTyping(true);
+
+      const token = getToken();
+      fetch('/pos/api/chat', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': 'Bearer ' + token
+        },
+        body: JSON.stringify({
+          message: photoPrompt,
+          history: history.slice(-10)
+        })
+      })
+        .then(function (resp) { return resp.json(); })
+        .then(function (data) {
+          const aiMsg = data.response || 'No pude identificar la parte. Intenta describirla con texto.';
+          addBubble(aiMsg, 'ai');
+          history.push({ role: 'assistant', content: aiMsg });
+
+          if (data.vehicle && data.vehicle.brand_id) {
+            addVehicleBanner(data.vehicle);
+          }
+          if (data.search_results && data.search_results.length > 0) {
+            addPartResults(data.search_results);
+          }
+        })
+        .catch(function (err) {
+          addBubble('Error al procesar imagen: ' + err.message, 'ai');
+        })
+        .finally(function () {
+          isSending = false;
+          document.getElementById('chatSend').disabled = false;
+          showTyping(false);
+        });
+    };
+    reader.readAsDataURL(file);
+  }
+
   function toggleChat() {
     isOpen = !isOpen;
     const panel = document.getElementById('chatPanel');