fix(v2): confirmed real Slack channel slug (chamados-suporte)

Two more real test-send attempts (both with the user's standing
authorization), each confirming a bit more of the pipeline and each
correctly caught/recorded/surfaced by the failure branch -- no message
ever actually reached Slack, exactly as the guard is designed to behave
on failure:

1. channel "CHAMADOS SUPORTE" (as literally given) -> channel_not_found
   (Slack channel identifiers are always lowercase-hyphenated).
2. channel "chamados-suporte" -> not_in_channel: the channel resolved
   correctly this time, but the Bot Coordenador app is not yet a member
   of that channel (chat.postMessage requires channel membership without
   the chat:write.public scope). This is a Slack-side action for the
   user (invite the bot to the channel), not fixable from n8n config.

Updated the channel value to the confirmed-correct slug. Reverted
SEND_ENABLED to false, workflow deactivated, temp webhook removed.

158/158 tests passing.

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

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

@@ -785,7 +785,7 @@
         "channelId": {
           "__rl": true,
           "mode": "name",
-          "value": "CHAMADOS SUPORTE"
+          "value": "chamados-suporte"
         },
         "text": "={{ $json.mensagem }}",
         "otherOptions": {}