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

tests/e2e/pos-checkout.spec.js

@@ -1,21 +1,71 @@
 const { test, expect } = require('@playwright/test');
 
-test.describe('Nexus POS — Checkout', () => {
-  test('POS sale page loads with cart', async ({ page }) => {
-    await page.goto('/pos/sale');
-    await expect(page.locator('#cartBody, .cart, #cartTable, .pos-cart')).toBeVisible({ timeout: 10000 });
-    const content = await page.locator('body').textContent();
-    expect(content).toMatch(/venta|carrito|total|pagar/i);
+const FAKE_TOKEN = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjk5OTk5OTk5OTksIm5hbWUiOiJUZXN0IFVzZXIifQ.signature';
+
+async function setupAuth(page) {
+  await page.goto('/pos/login');
+  await page.evaluate((token) => {
+    localStorage.setItem('pos_token', token);
+    localStorage.setItem('pos_tenant_id', '11');
+  }, FAKE_TOKEN);
+}
+
+async function mockPOSAPIs(page) {
+  await page.route('/pos/api/register/current', async (route) => {
+    await route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({ register: { register_number: 1 } }),
+    });
   });
 
-  test('catalog search from POS shows results', async ({ page }) => {
+  await page.route(/\/pos\/api\/inventory\/items\?q=.*&per_page=.*/, async (route) => {
+    await route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({
+        data: [
+          {
+            id: 1,
+            part_number: 'TEST-001',
+            name: 'Producto de prueba',
+            brand: 'TestBrand',
+            stock: 10,
+            price_1: 100.0,
+            price_2: 90.0,
+            price_3: 80.0,
+          },
+        ],
+      }),
+    });
+  });
+}
+
+test.describe('Nexus POS — Checkout', () => {
+  test('POS page loads with cart', async ({ page }) => {
+    await setupAuth(page);
+    await mockPOSAPIs(page);
     await page.goto('/pos/sale');
-    const searchInput = page.locator('#productSearch, #searchInput, input[placeholder*="buscar" i]').first();
-    await expect(searchInput).toBeVisible({ timeout: 10000 });
-    await searchInput.fill('freno');
+
+    await expect(page).toHaveTitle(/Nexus Autoparts/i);
+    await expect(page.locator('#cartItems')).toBeVisible();
+    await expect(page.locator('#cartBody')).toBeVisible();
+    await expect(page.locator('#btnCobrar')).toBeVisible();
+  });
+
+  test('catalog search from POS', async ({ page }) => {
+    await setupAuth(page);
+    await mockPOSAPIs(page);
+    await page.goto('/pos/sale');
+
+    const searchInput = page.locator('#itemSearch');
+    await expect(searchInput).toBeVisible();
+    await searchInput.fill('test');
     await searchInput.press('Enter');
-    await page.waitForTimeout(800);
-    const hasDropdown = await page.locator('.search-dropdown, #searchDropdown, .parts-grid').first().isVisible().catch(() => false);
-    expect(hasDropdown || true).toBe(true);
+
+    // Assert search results dropdown/grid appears
+    const results = page.locator('#searchResults');
+    await expect(results).toBeVisible({ timeout: 5000 });
+    await expect(results).toContainText('Producto de prueba');
   });
 });