fix(alerts): limit alerts to 500 per type in SQL + frontend pagination with 'Ver más' + summary bar

pos/blueprints/inventory_bp.py

@@ -1111,9 +1111,18 @@ def api_alerts():
     """Get stock alerts (zero, low, over)."""
     conn = get_tenant_conn(g.tenant_id)
     branch_id = request.args.get('branch_id', g.branch_id)
-    alerts = get_alerts(conn, branch_id)
+    limit = min(int(request.args.get('limit', 500)), 2000)
+    alerts = get_alerts(conn, branch_id, limit_per_type=limit)
     conn.close()
-    return jsonify({'data': alerts, 'count': len(alerts)})
+
+    # Count totals by severity for UI summary
+    counts = {'critical': 0, 'warning': 0, 'info': 0, 'total': 0}
+    for a in alerts:
+        counts['total'] += 1
+        if a['severity'] in counts:
+            counts[a['severity']] += 1
+
+    return jsonify({'data': alerts, 'count': len(alerts), 'counts': counts, 'limit_per_type': limit})
 
 
 @inventory_bp.route('/items/<int:item_id>/history', methods=['GET'])