fix(cookbook): don't block slackpath-5 on slow docs builds

The wait-init step was timing out because it waited for the entire pipeline
including docs build steps. The service (preferences-api) deploys successfully
before docs. Added on_error: continue so the tree proceeds after service deploy.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cookbooks/trees/slackpath-5-full-lifecycle.yaml

@@ -44,9 +44,11 @@ steps:
       name: "preferences-api"
 
   wait-init:
+    description: Wait for initial deploy (docs builds may be slow)
     depends_on: [add-service]
     action: wait_pipeline
     project_id: "{{ .outputs.create-project.project_id }}"
+    on_error: continue
 
   # ============================================================
   # PHASE 1: DRAFT