fix: template prompt bloat and variable substitution failures

- chapter_polish: remove sections:deliverables — chapter text already in
  {chapter_text}; this caused 150KB+ prompts for late chapters (40MB logs)
- chapter_roundtable: require structured CONSENSUS REACHED block so
  key_changes is always formatted as an extractable string; change
  key_changes schema from list to string to match
- book_chapter: remove sections:history to reduce context; restructure
  Pass 0 to plan-only (no prose output) so the chapter is only written
  once in Pass 1 instead of twice; add explicit instruction in package
  hint to copy full chapter_text into spawn context
- short_story: remove sections:history and sections:deliverables (standalone
  task, needs neither); restructure Pass 0 to plan-only, Pass 1 to write;
  add note to handle literal {genre_name} placeholders gracefully
- recipe_develop, ai_article_write, blog_write: remove sections:history
  (these standalone tasks do not need full project conversation history;
  deliverables kept so they can read the research/plan file)

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

templates/chapter_roundtable.yml

@@ -51,13 +51,21 @@ steps:
         - Continuity with prior chapters and world rules
 
       If the group has reached sufficient consensus for the polish step,
-      end your response with: CONSENSUS REACHED
+      end your response with this EXACT block — no variations, no paraphrasing:
+
+      CONSENSUS REACHED
+      CRITIQUE: [One concise paragraph summarizing the full editorial consensus]
+      KEY CHANGES:
+      - [Specific change 1]
+      - [Specific change 2]
+      - [Specific change 3 if needed]
+      VERDICT: [PASS / REVISE / REWRITE]
 
   - type: package
     schema:
       consensus_critique: string
       chapter_verdict: string
-      key_changes: list
+      key_changes: string
     spawn:
       - task_type: chapter_polish
         task_name: "Polish: {chapter_ref}"