feat(effort): entry level on every skill next to its model pin (BDR-108)

- lib/effort-pins.txt (map) + lib/effort-pins.sh (idempotent re-apply)
  replace the hardcoded brainstorming/writing-plans loop; called after the
  last vendoring step of install-plugins.sh AND update-all.sh (the resync
  dropped the pins until the next make plugin)
- design stack high uniform (last loaded wins), superpowers, agent-skills,
  21st pack pinned from the map; skills-perso low, pdf-translate medium,
  site-motion high
- doctrine: design stack loads paired with the first Read; one level per
  stack (CLAUDE.global.md, lib/effort-shift.md)
- lib/effort-audit.py prints thinking coverage per scope (sub-agent records
  carry no thinking count on ~94 % of requests)
- census map-driven + fixture suite lib/tests/effort-pins.test.sh; docs
  README/USAGE/CHANGELOG; contract + TODO plan

skills/pdf-translate/SKILL.md

@@ -1,5 +1,6 @@
 ---
 name: pdf-translate
+effort: medium
 description: Use when translating a PDF (especially OCR or image-based) to another language and producing faithful HTML output. Handles image extraction, layout preservation, contextual translation, and style-matched reconstruction. Triggers on "translate this PDF", "PDF en francais", "convert PDF to HTML translated", "traduire ce document".
 ---