feat: MercadoLibre integration + inventory bulk publish + WhatsApp bridge fixes

- Add MercadoLibre OAuth, listings, orders, webhooks and category search
- New marketplace_external_bp.py, meli_service.py, marketplace_external_service.py
- New marketplace_external.html/js with ML management UI
- Inventory: bulk publish to ML with category autocomplete, listing type and shipping selectors
- Inventory: new .btn--meli styles, select/label CSS fixes
- WhatsApp bridge: rate limiting, 440/515/408 error handling, stale watchdog
- DB migration v3.4_meli_integration.sql for marketplace_listings, orders, sync_queue
- Add Celery tasks for ML sync and webhook processing
- Sidebar: MercadoLibre navigation link

pos/services/whatsapp_service.py

@@ -105,6 +105,7 @@ def process_incoming(webhook_data):
     #  - For 'text' messages → conversation or extendedTextMessage
     #  - For 'image'/'video' → the caption (may be empty)
     #  - For 'audio' → empty (filled in later by Whisper transcription)
+    #  - For 'location' → synthetic text with coordinates
     if media_kind == 'text':
         text = (
             message.get('conversation', '')
@@ -114,6 +115,10 @@ def process_incoming(webhook_data):
     else:
         text = media_caption
 
+    # Location fields (from bridge classification)
+    latitude = data.get('latitude')
+    longitude = data.get('longitude')
+
     return {
         'phone': phone,
         'jid': remote_jid,
@@ -125,4 +130,20 @@ def process_incoming(webhook_data):
         'media_mimetype': media_mimetype,
         'is_voice_note': is_voice_note,
         'push_name': push_name,
+        'latitude': latitude,
+        'longitude': longitude,
     }
+
+
+def send_image(phone, caption, base64_image, bridge_url=None):
+    """Send an image message via the Baileys bridge."""
+    url = _get_url(bridge_url)
+    try:
+        return requests.post(
+            f'{url}/send-image',
+            headers=HEADERS,
+            json={'phone': phone, 'caption': caption, 'base64': base64_image},
+            timeout=15
+        ).json()
+    except Exception as e:
+        return {'error': str(e)}