feat(api): add BNPL, ERP, WhatsApp Cloud, Supplier Portal stubs

- bnpl_bp.py: APLAZO/Kueski/Clip application workflow (mock)
- erp_bp.py: Aspel/CONTPAQi/SAP/Odoo sync jobs (mock)
- whatsapp_cloud_bp.py: Meta Cloud API webhook, messages, templates
- supplier_portal_bp.py: demand by zone/branch and top-parts analytics
- app.py: register all new blueprints

pos/blueprints/erp_bp.py

@@ -0,0 +1,79 @@
+"""ERP Sync Blueprint — Integration with Aspel, CONTPAQi, SAP, Odoo.
+
+Stubs with architecture ready for real connectors.
+"""
+from flask import Blueprint, request, jsonify, g
+from functools import wraps
+import uuid
+from datetime import datetime
+
+erp_bp = Blueprint('erp', __name__, url_prefix='/pos/api/erp')
+
+
+from middleware import require_auth
+
+
+# ─── Mock sync jobs ───
+_mock_jobs = {}
+
+
+@erp_bp.route('/providers', methods=['GET'])
+@require_auth()
+def list_providers():
+    return jsonify({
+        'providers': [
+            {'id': 'aspel_sae', 'name': 'Aspel SAE', 'type': 'file_exchange', 'enabled': False},
+            {'id': 'contpaqi', 'name': 'CONTPAQi', 'type': 'file_exchange', 'enabled': False},
+            {'id': 'sap_b1', 'name': 'SAP Business One', 'type': 'api', 'enabled': False},
+            {'id': 'odoo', 'name': 'Odoo', 'type': 'api', 'enabled': False},
+        ]
+    })
+
+
+@erp_bp.route('/sync', methods=['POST'])
+@require_auth()
+def start_sync():
+    data = request.get_json() or {}
+    provider = data.get('provider')
+    sync_type = data.get('sync_type', 'sales')  # sales, inventory, customers
+    if not provider:
+        return jsonify({'error': 'provider is required'}), 400
+
+    job_id = str(uuid.uuid4())
+    _mock_jobs[job_id] = {
+        'id': job_id,
+        'provider': provider,
+        'sync_type': sync_type,
+        'status': 'queued',
+        'records_synced': 0,
+        'errors': [],
+        'created_at': datetime.utcnow().isoformat(),
+        'started_at': None,
+        'finished_at': None,
+    }
+    return jsonify(_mock_jobs[job_id]), 201
+
+
+@erp_bp.route('/sync/<job_id>', methods=['GET'])
+@require_auth()
+def get_sync_status(job_id):
+    job = _mock_jobs.get(job_id)
+    if not job:
+        return jsonify({'error': 'Job not found'}), 404
+    return jsonify(job)
+
+
+@erp_bp.route('/sync/<job_id>/run', methods=['POST'])
+@require_auth()
+def run_sync(job_id):
+    """Mock execute sync (in production this triggers a Celery task)."""
+    job = _mock_jobs.get(job_id)
+    if not job:
+        return jsonify({'error': 'Job not found'}), 404
+    job['status'] = 'running'
+    job['started_at'] = datetime.utcnow().isoformat()
+    # Mock completion
+    job['status'] = 'completed'
+    job['records_synced'] = 42
+    job['finished_at'] = datetime.utcnow().isoformat()
+    return jsonify(job)