feat(v2): REAL Slack send confirmed working end-to-end

After the user added the missing OAuth scopes (channels:join,
chat:write.public) and reinstalled the Slack App, updated the credential
with the refreshed token and retried the real test send: SUCCESS. The
digest message was actually posted to #chamados-suporte (channel
C0BJNBTPFT5) by "Bot Coordenador", confirmed via the real Slack API
response (ok:true, real message ts/channel/bot_profile returned).
Code - Registrar Envio Sucesso correctly recorded status:'success' --
this record is intentionally left in place (not cleared like the earlier
failed-test rows), since it now correctly represents a real send and its
whole purpose is to prevent a duplicate resend of today's digest.

Also found and fixed a real cosmetic bug from that same successful send:
n8n's Slack node appends an "Automated with this n8n workflow" link
footer by default (otherOptions.includeLinkToWorkflow defaults to true)
-- not part of the message spec (minimal digest only). Disabled it.
Added a regression test.

Reverted SEND_ENABLED to false and deactivated pending final user
confirmation before permanent production activation.

159/159 tests passing.

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

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

@@ -788,7 +788,9 @@
           "value": "C0BJNBTPFT5"
         },
         "text": "={{ $json.mensagem }}",
-        "otherOptions": {}
+        "otherOptions": {
+          "includeLinkToWorkflow": false
+        }
       },
       "credentials": {
         "slackApi": {