feat: gate writer sections on a % teach: block (SP025)

Rewrite references/pedagogy.md around recite-vs-teach: reader model,
coverage density (sections_in is cite permission, not a to-do list),
intuition-before-formula three-beat, and paper-jump filling.

Every notes/sections/sec-*.tex must now answer gap / takeaway / jump /
omit above the first \section. lint.py checks presence only (it cannot
judge honesty); files opening with "% generated by" are exempt.

- scripts/lint.py: SP025 + is_writer_section / teach_gaps helpers
- tests/no-teach-block/: fixture with takeaway only, wired into test.sh
- examples/*: all 14 writer sections get real teach blocks
- SKILL.md, references/{agents,antipatterns,checklist}.md, DESIGN.md,
  assets/notes-template.tex: route writers and consistency agent
  through pedagogy.md

references/agents.md

@@ -4,11 +4,13 @@ Must split when pages > 12 **or** top sections > 4 **or** redraws ≥ 2 **or** t
 
 Writer jobs are lecture rows in `outline.md`, not `coverage.sections_in`. Outline writes `ledger.yaml`, `outline.md`, `notes.tex` inputs, and `F*.request.md`. Writers only touch their `sec-XX.tex`. Figure agents only see the request.
 
+Outline, writers, and consistency read `references/pedagogy.md`. Consistency flags missing `% teach:` blocks and section-order recaps.
+
 ```
 $superpaper <源> 请 spawn 多 sub agents，隔离上下文：
   - 1 个 outline agent：ledger.yaml + outline.md
-  - N 个 writer agents：sections/sec-XX.tex
+  - N 个 writer agents：先读 references/pedagogy.md；sections/sec-XX.tex
   - 每个计划重绘图 1 个 figure agent：F*.request.md + sibling skill
-  - 1 个 consistency agent：符号、术语、claim 覆盖
+  - 1 个 consistency agent：符号、术语、claim 覆盖、是否复述（pedagogy.md）
 完成后用 scripts/lint.py 与 build.sh 收口。
 ```