fix(v2): envio-digest insert nodes were missing the required columns mapping

Found running the real Slack test send (with the user's explicit
confirmation to try SEND_ENABLED=true once): the Slack node itself fired
correctly and got a real response back from Slack's API ("invalid_arguments"
-- confirms the pipeline mechanics, credential and node config work end
to end up to that point). Separately, once the failure branch tried to
record it, "Data Table - Registrar Envio Digest (Falha)" crashed with
"Cannot convert undefined or null to object" inside n8n's own insert
operation -- both new envio-digest insert nodes had operation:"insert"
and dataTableId but no "columns" mapping, which is a required property
for insert/update/upsert (confirmed via get_node nodes-base.dataTable).
Fixed both nodes with the same columns.mappingMode:"defineBelow" shape
already used by the existing "Data Table - Registrar Shadow Run" node.

Added a regression test scanning every dataTable node with an insert/
update/upsert operation for a columns.mappingMode.

158/158 tests passing.

Separately (not fixed here, needs the user): the actual Slack
"invalid_arguments" error suggests $vars.SLACK_CHANNEL_TECNICO isn't
resolving to a valid channel on this n8n instance -- no tool available
to this agent can list/inspect n8n instance Variables to confirm. Left
SEND_ENABLED=false and the workflow inactive pending the user's input on
the correct channel.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

n8n/deployed/coordenador-glpi-v2.n8n.json

@@ -850,6 +850,18 @@
         "dataTableId": {
           "mode": "name",
           "value": "coordenador_glpi_envios_digest"
+        },
+        "resource": "row",
+        "columns": {
+          "mappingMode": "defineBelow",
+          "value": {
+            "report_date": "={{ $json.report_date }}",
+            "run_type": "={{ $json.run_type }}",
+            "message_hash": "={{ $json.message_hash }}",
+            "sent_at": "={{ $json.sent_at }}",
+            "status": "={{ $json.status }}",
+            "error_detail": "={{ $json.error_detail }}"
+          }
         }
       }
     },
@@ -867,6 +879,18 @@
         "dataTableId": {
           "mode": "name",
           "value": "coordenador_glpi_envios_digest"
+        },
+        "resource": "row",
+        "columns": {
+          "mappingMode": "defineBelow",
+          "value": {
+            "report_date": "={{ $json.report_date }}",
+            "run_type": "={{ $json.run_type }}",
+            "message_hash": "={{ $json.message_hash }}",
+            "sent_at": "={{ $json.sent_at }}",
+            "status": "={{ $json.status }}",
+            "error_detail": "={{ $json.error_detail }}"
+          }
         }
       }
     },