feat(skills): добавлен скилл brainstorm-with-docs (v1)

- Зачем:
  - нужен ручной скилл для брейнсторма и дизайна, который удерживает
    словарь смыслов (CONTEXT.md) и лёгкие ADR, активно прожаривает план
    и не сваливается в реализацию.
- Что:
  - SKILL.md: процесс (контекст → классификация → декомпозиция →
    грилл → синтез опций → подтверждение → артефакт), единый HARD-GATE
    «исследуй, но не меняй состояние» с поправкой на auto mode.
  - artifacts/: шаблоны spec, research-note, adr, runbook, prd, context
    (по файлу на тип для progressive disclosure).
  - README.md с MIT-атрибуцией grill-with-docs (Pocock) и brainstorming
    (obra/superpowers); шов для будущей фазы дивергенции в шаге 5.
  - frontmatter переносим: Claude читает все поля, Codex — name+description.
- Проверка:
  - python3 yaml-парс frontmatter; markdown-ссылки на artifacts/ резолвятся.

agents/.agents/skills/brainstorm-with-docs/artifacts/adr.md

@@ -0,0 +1,40 @@
+# ADR — Architectural Decision Record
+
+ADRs live in `docs/adr/` with sequential numbering: `0001-slug.md`,
+`0002-slug.md`, etc. Create `docs/adr/` lazily — only when the first ADR is
+needed. To number a new one, scan `docs/adr/` for the highest number and add one.
+
+## When to offer an ADR
+
+Offer one only when **all three** are true:
+
+1. **Hard to reverse** — the cost of changing your mind later is meaningful.
+2. **Surprising without context** — a future reader will look at the code and
+   wonder "why on earth did they do it this way?"
+3. **The result of a real trade-off** — there were genuine alternatives and one
+   was picked for specific reasons.
+
+If any of the three is missing, skip it. Easy to reverse → you'll just reverse
+it. Not surprising → nobody will wonder. No real alternative → nothing to record
+beyond "we did the obvious thing". Do not create an ADR for every small choice.
+
+## Template
+
+```markdown
+# {Short title of the decision}
+
+{1-3 sentences: what's the context, what we decided, and why.}
+```
+
+That's it. An ADR can be a single paragraph. The value is recording *that* a
+decision was made and *why* — not in filling out sections.
+
+## Optional sections
+
+Add these only when they earn their place (most ADRs won't need them):
+
+- **Status** frontmatter (`proposed | accepted | deprecated | superseded by
+  ADR-NNNN`) — useful when decisions get revisited.
+- **Considered options** — only when the rejected alternatives are worth
+  remembering (otherwise someone re-proposes them in six months).
+- **Consequences** — only when non-obvious downstream effects need calling out.