fix(ai_article_research): use type: spawn instead of package/IntakeResponse

IntakeResponse packet type is for intake routing only, not child task creation.
Replace with type: spawn (same pattern as book_research.yml) to correctly
spawn the ai_article_plan task after research completes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

templates/ai_article_research.yml

@@ -52,26 +52,10 @@ steps:
   - type: document
     filename: "{{task_name_slug}}"
 
-  - type: package
-    packet_type: IntakeResponse
-    hint: |
-      Create exactly ONE follow-up task.
-
-      - task_name: "Plan Article Series"
-      - task_type: "ai_article_plan"
-      - description: "Using the research deliverable, plan exactly 10 standalone articles for
-          this series. Each article is a 5-minute read (~800-1000 words) for the target audience
-          described in the project. You choose the topics based on the research. Then spawn 10
-          ai_article_write tasks."
-      - depends_on: ""
-    schema:
-      actions:
-        - type: create_task
-          task_name: "string"
-          agent_name: "string"
-          task_type: "string"
-          description: "string"
-          depends_on: "string"
+  - type: spawn
+    task_type: ai_article_plan
+    task_name: "Plan Article Series: {project.name}"
+    message: "{task.message}"
 
   - type: close
     rag_update: true