docs: sync to Claude Code v2.1.278 (#183)

* docs: sync to Claude Code v2.1.278

Type: docs

Audit of the tutorial against Claude Code 2.1.278 (repo baseline was
2.1.263). Fixes claims the repo asserts that are now false; new-feature
coverage is English-only.

P0 - the repo stated the opposite of current behavior:
- AGENTS.md: the claude-md skill said Claude Code "does not read
  AGENTS.md directly" in all 5 languages. It has since v2.1.277, when no
  CLAUDE.md exists at or above the working directory.
- /output-style: listed as "Removed in v2.1.91" in 5 languages and in
  09-advanced-features. Re-added in v2.1.269; row moved out of the
  Deprecated Commands table.
- Permission rules: setup-auto-mode-permissions.py seeded Write(*),
  Glob(*) and NotebookEdit(*), which Claude Code accepts but never
  consults and warns about at startup. Removed; same fix in the
  config-examples.json profile and the 06/09 category tables.
- taskOutputMaxChars: documented as live. The TaskOutput tool was
  removed in v2.1.278 and the key is inert.

P1:
- Dynamic workflow "medium" guideline is fewer than 10 agents, not 15;
  the default is small on Pro plans since v2.1.271.
- Todo-tool availability restated as the official allowlist (Claude 3.x,
  Opus 4-4.7, Sonnet 4-4.6, Haiku 4.5) instead of a denylist; 23 sites
  across 5 languages.
- Memory hierarchy now notes the AGENTS.md fallback.
- Auto-mode classifier cost qualified: not charged on Enterprise plans
  and Claude API accounts since v2.1.278.

P3 (English only): full AGENTS.md section in 02-memory; omitClaudeMd
subagent field; plugin eval / --json / --accept-command / --marketplace;
maxEffortLevel, bashEditDiffEnabled, syncClaudeAi*, 4 env vars,
--system-prompt-snapshot, --plugin-dir folders; send-now key and Monitor
deadlines; checkpoints subagent-edit limitation.

Learning skills audited clean: 100 quiz questions and 100 Review
pointers all valid, 20 self-assessment options correctly mapped.

Cross-file anchors: 15 broken before, 15 after, 0 introduced.

* docs: address review — stale version stamps, /output-style re-add, permission tables

ja/02-memory/README.md

@@ -227,6 +227,7 @@ Claude Code は多階層のメモリシステムを使う。Claude Code 起動
 
 3. **Project Memory** — チーム共有のコンテキスト（バージョン管理対象）
    - `./.claude/CLAUDE.md` または `./CLAUDE.md`（リポジトリのルート）
+   - v2.1.277 以降、作業ディレクトリとその上位に `CLAUDE.md` も `CLAUDE.local.md` も存在しない場合、同じ階層で代わりに `./AGENTS.md` が読み込まれる。`/config` の **Project instructions** で制御する
 
 4. **Project Rules** — モジュール式・トピック別のプロジェクト指示
    - `./.claude/rules/*.md`
@@ -1206,10 +1207,11 @@ Claude はどのメモリファイルを更新するかを尋ねる。
 - [公式メモリドキュメント](https://code.claude.com/docs/en/memory) — Anthropic ドキュメント
 
 ---
-**最終更新**: 2026 年 8 月 25 日
-**Claude Code バージョン**: 2.1.245
+**最終更新**: 2026 年 9 月 19 日
+**Claude Code バージョン**: 2.1.278
 **Sources**:
 - https://code.claude.com/docs/en/memory
+- https://code.claude.com/docs/en/memory#agents-md
 - https://code.claude.com/docs/en/settings
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.117
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.119