TODO: Delete orphan Woodpecker secret tf_var_slack_webhook_url

todo-delete-woodpecker-slack-secret Doc

todo done
QA nit from Phase 16 (pal-e-platform PR #83): Woodpecker CI still has a tf_var_slack_webhook_url secret configured in the repo settings. The Slack receiver and all code references have been removed — this secret is now orphaned and should be deleted from Woodpecker.
Repo: forgejo_admin/pal-e-platform (Woodpecker CI settings)
Source: phase-platform-16-alert-tuning (16a QA nit)