fix(jenkins): update trigger method to use pollSCM and provide upgrade recommendations for Generic Webhook Trigger

ci/Jenkinsfile

@@ -70,22 +70,34 @@ pipeline {
 
     /* -------------------------------------------------------------------------
      *  TRIGGER
-     *  Il plugin Generic Webhook Trigger deve essere installato in Jenkins.
-     *  Se non presente: Manage Jenkins → Plugin Manager → cerca "Generic Webhook Trigger".
+     *
+     *  ATTUALE: pollSCM — Jenkins interroga il repo ogni 2 minuti e parte
+     *  se ci sono nuovi commit su main. Nessun plugin aggiuntivo richiesto.
+     *
+     *  UPGRADE CONSIGLIATO → Generic Webhook Trigger (risposta immediata):
+     *    1. Manage Jenkins → Plugin Manager → "Generic Webhook Trigger" → Install
+     *    2. Sostituire il blocco triggers con:
+     *
+     *       triggers {
+     *           GenericTrigger(
+     *               genericVariables: [
+     *                   [key: 'GITEA_REF',    value: '$.ref'],
+     *                   [key: 'GITEA_BEFORE', value: '$.before'],
+     *                   [key: 'GITEA_AFTER',  value: '$.after'],
+     *               ],
+     *               causeString:               'Push Gitea su $GITEA_REF',
+     *               token:                     'homeassistant-addons',
+     *               printContributedVariables: true,
+     *               regexpFilterText:          '$GITEA_REF',
+     *               regexpFilterExpression:    'refs/heads/main'
+     *           )
+     *       }
+     *
+     *    3. Creare webhook in Gitea → Settings → Webhooks:
+     *       URL: https://pipelines.mt-home.uk/generic-webhook-trigger/invoke?token=homeassistant-addons
      * ----------------------------------------------------------------------- */
     triggers {
-        GenericTrigger(
-            genericVariables: [
-                [key: 'GITEA_REF',    value: '$.ref'],
-                [key: 'GITEA_BEFORE', value: '$.before'],
-                [key: 'GITEA_AFTER',  value: '$.after'],
-            ],
-            causeString:               'Push Gitea su $GITEA_REF',
-            token:                     'homeassistant-addons',
-            printContributedVariables: true,
-            regexpFilterText:          '$GITEA_REF',
-            regexpFilterExpression:    'refs/heads/main'
-        )
+        pollSCM('H/2 * * * *')
     }
 
     environment {