Sprint 56a: PASS 1 + SELF-CHECK locked chapter hook enforcement

- PASS 1: new requirement — FIRST LINE must resolve LOCKED PREVIOUS
  CHAPTER HOOK if present in draft prompt
- SELF-CHECK: item 6 — validate opening paragraph answers locked hook;
  add resolution sentence if missing

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

templates/book_chapter.yml

@@ -99,6 +99,8 @@ steps:
 
       Requirements:
         - Start with the FIRST LINE you planned — make it continue naturally from the previous chapter
+        - If the draft prompt contains a line starting with "LOCKED PREVIOUS CHAPTER HOOK:",
+          your FIRST LINE MUST directly resolve that hook — the reader expects the answer immediately
         - Follow the KEY BEATS in order, but write with full scene depth — don't skip
         - All character names must be consistent with the bible/outline
         - Every dialogue exchange must be tight and voice-distinct
@@ -145,6 +147,10 @@ steps:
            or missing chapter title? Flag and fix.
         5. WORD FLOOR: Is the draft within 10% of {chapter_target_words}? Flag only if
            critically short (more than 20% under target) — do not expand for style.
+        6. OPENING HOOK: Check the PASS 0 draft prompt ({steps[0].text}) for a line labeled
+           "LOCKED PREVIOUS CHAPTER HOOK:". If present, verify the chapter's opening paragraph
+           directly resolves it. If not, add a brief resolution sentence at the opening —
+           do not leave a locked hook unanswered.
 
       ALLOWED CORRECTIONS:
         - Fix a wrong character name to match the canon name