feat(whatsapp): QWEN primary AI backend, Hermes fallback, conversation history, vehicle persistence, demo prompts

- Add QWEN (qwen3.6) as primary AI backend with short system prompt
- Hermes remains as fallback with 45s timeout
- Increase QWEN timeout to 35s, max_tokens to 4000
- Add conversation history loading from whatsapp_messages (last 4 msgs)
- Persist detected vehicle in whatsapp_sessions table
- Add 'limpiar chat' / 'nuevo chat' / 'reset' commands to clear history
- Fix CSS conflict: rename whatsapp chat-panel classes to wa-chat-panel
- Fix JS ID conflicts with chat.js widget (waChatPanel, waChatMessages, etc.)
- Improve no-stock response: conversational with alternatives
- Split search_query by | for multi-part lookups
- Add DEMO_PROMPTS.md and DEMO_PROMPTS_V2.md

pos/blueprints/catalog_bp.py

@@ -356,8 +356,9 @@ def search():
     if not q or len(q) < 2:
         return jsonify({'data': []})
     limit = request.args.get('limit', 50, type=int)
+    mye_id = request.args.get('mye_id', type=int)
     def _do(master, tenant, branch_id):
-        data = catalog_service.smart_search(master, q, tenant, branch_id, limit)
+        data = catalog_service.smart_search(master, q, tenant, branch_id, limit, mye_id)
         return jsonify({'data': data})
     return _with_conns(_do)