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

08-checkpoints/README.md

@@ -246,6 +246,7 @@ Checkpoints have the following limitations:
 - **Bash command changes NOT tracked** - Operations like `rm`, `mv`, `cp` on the filesystem are not captured in checkpoints
 - **External changes NOT tracked** - Changes made outside Claude Code (in your editor, terminal, etc.) are not captured
 - **Not a replacement for version control** - Use git for permanent, auditable changes to your codebase
+- **Subagent edits NOT restored** - Files edited by a subagent are untracked, so `/rewind` leaves them as they are; the exception is a foreground `context: fork` skill, whose edits are restored like the main session's
 
 > **v2.1.216 update**: `/rewind` no longer restores or deletes files through symlinks or hard links at tracked paths. If a tracked path resolves through a symlink or hard link, rewind skips it rather than following the link, and it reports how many paths it skipped for this reason.
 
@@ -336,8 +337,8 @@ Remember: checkpoints are not a replacement for git. Use checkpoints for rapid e
 
 ---
 
-**Last Updated**: August 25, 2026
-**Claude Code Version**: 2.1.245
+**Last Updated**: September 19, 2026
+**Claude Code Version**: 2.1.278
 **Sources**:
 - https://code.claude.com/docs/en/checkpointing
 - https://code.claude.com/docs/en/settings