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/context.md

@@ -0,0 +1,53 @@
+# CONTEXT.md — Shared Project Language
+
+`CONTEXT.md` is a **glossary and nothing else**. It exists so that the user, the
+code, and future agents use the same words for the same concepts. It is totally
+devoid of implementation details, decisions, plans, or work logs.
+
+A single `CONTEXT.md` lives at the repo root. If a `CONTEXT-MAP.md` exists at the
+root, the repo has multiple contexts — read it to find which `CONTEXT.md` the
+current topic belongs to. (Multi-context handling is deliberately light in v1.)
+
+Create the file lazily — only when the first term is actually worth recording.
+
+## Structure
+
+```markdown
+# {Context Name}
+
+{One or two sentences: what this context is and why it exists.}
+
+## Language
+
+**Order**:
+A customer's request to purchase one or more items.
+_Avoid_: Purchase, transaction
+
+**Invoice**:
+A request for payment sent to a customer after delivery.
+_Avoid_: Bill, payment request
+
+**Customer**:
+A person or organisation that places orders.
+_Avoid_: Client, buyer, account
+```
+
+## Rules
+
+- **Be opinionated.** When several words mean the same thing, pick the best one
+  and list the rest under `_Avoid_`.
+- **Keep definitions tight.** One or two sentences. Define what it *is*, not what
+  it *does*.
+- **Only project-specific terms.** General programming concepts (timeouts, retry,
+  cache) don't belong, even if the project uses them heavily. Ask: is this unique
+  to this project's domain, or generic? Only the former belongs.
+- **Group under subheadings** when natural clusters emerge; a flat list is fine
+  otherwise.
+
+## What does NOT go in CONTEXT.md
+
+- implementation details
+- specs, decisions, or rejected alternatives → spec / ADR
+- operational procedures → runbook
+- validation rules for the current work → spec
+- work logs, temporary notes, speculative ideas