docs: sync to Claude Code v2.1.235 (#174)

* docs: sync to Claude Code v2.1.235

Syncs the tutorial repo from v2.1.233 to v2.1.235, fixes a fabricated
plugin-command reference and a wrong lesson-quiz answer, closes translation
fan-out gaps, and documents six new features from v2.1.234/v2.1.235.

* docs(slash-commands): scope v2.1.234 dialog-command claims to the fullscreen TUI

The v2.1.234 changelog carries two separate entries: /permissions opening
mid-turn unconditionally, and the /add-dir, /autocompact, /theme, /help,
/config and /advisor dialogs opening mid-turn in the fullscreen TUI. The
sync flattened both into one unqualified bullet, so a reader on the default
renderer would find the described behavior absent.

Also corrects the CATALOG usage-limit auto-continue row, which described an
on-by-default feature as opt-in ("Enable via /config"); the changelog says
"turn it off in /config".

* docs(advanced-features): correct spellcheck value shape, default, and scope

settings.md documents `spellcheck` as object-valued
(`{"enabled": true, "language": "en_GB"}`) and read from user settings, the
--settings flag, and managed settings only; interactive-mode.md adds that it
is off by default and needs aspell, hunspell, or ispell on PATH. CATALOG told
readers to set a bare `"spellcheck": true`, and both settings tables sit under
preambles promising project-scope settings work, which for this key they do
not.

Also repoints CATALOG's hook-configuration example at pre-tool-check.sh; the
table rename left the example on validate-bash.py, which is not in 06-hooks/.

* docs(plugins): drop the unsupported claim that /plugin update does not exist

The sync asserted "Updating is CLI-only — there is no `/plugin update` slash
command". The plugins reference contradicts that: it refers to running
`/plugin update` twice in present tense (the cache-key section, and the
explicit-version row that says `/plugin update` reports "already at the
latest version"). The v2.1.235 binary carries no `/plugin update` string and
its own update notices point at `claude plugin update <name>` in a terminal,
so the sources conflict and neither absolute is safe to teach.

Recommends the CLI form on its documented merits instead of asserting a
negative. Mirrored to vi/ja/zh/uk and to the lesson-quiz Q8 explanation,
which taught the same false negative. Q8's correct answer is unchanged.

* docs(advanced-features): complete the v2.1.234 env-var fan-out and 04 TOC (#175)

The env-var block was still headed (v2.1.221-v2.1.233) and omitted both
variables v2.1.234 added: CLAUDE_CODE_PROJECT_DIR_NAME, which had reached
only 10-cli and CATALOG, and CLAUDE_CODE_GOAL_CHECKIN_MINUTES, which was in
prose and a CATALOG row but no env-var table.

Also adds the one missing 04-subagents TOC entry: Additional Resources was
the only H2 without one, leaving the reconciled TOC at 26 of 27 sections.

README.md

@@ -12,7 +12,7 @@
 [![GitHub Stars](https://img.shields.io/github/stars/luongnv89/claude-howto?style=flat&color=gold)](https://github.com/luongnv89/claude-howto/stargazers)
 [![GitHub Forks](https://img.shields.io/github/forks/luongnv89/claude-howto?style=flat)](https://github.com/luongnv89/claude-howto/network/members)
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](LICENSE)
-[![Version](https://img.shields.io/badge/version-2.1.220-brightgreen)](CHANGELOG.md)
+[![Version](https://img.shields.io/badge/version-2.1.235-brightgreen)](CHANGELOG.md)
 [![Claude Code](https://img.shields.io/badge/Claude_Code-2.1+-purple)](https://code.claude.com)
 
 🌐 **Language / Ngôn ngữ / 语言 / Мова:** [English](README.md) | [Tiếng Việt](vi/README.md) | [中文](zh/README.md) | [Українська](uk/README.md) | [日本語](ja/README.md)
@@ -102,7 +102,7 @@ Run `/lesson-quiz [topic]` after each module. The quiz pinpoints what you missed
 
 - **GitHub stars** from developers who use Claude Code daily
 - **Forks** from teams adapting this guide for their own workflows
-- **Actively maintained** — synced with every Claude Code release (latest: v2.1.220, July 2026)
+- **Actively maintained** — synced with every Claude Code release (latest: v2.1.235, August 2026)
 - **Community-driven** — contributions from developers who share their real-world configurations
 
 [![Star History Chart](https://api.star-history.com/svg?repos=luongnv89/claude-howto&type=Date)](https://star-history.com/#luongnv89/claude-howto&Date)
@@ -873,8 +873,8 @@ MIT License - see [LICENSE](LICENSE). Free to use, modify, and distribute. The o
 
 ---
 
-**Last Updated**: August 15, 2026
-**Claude Code Version**: 2.1.233
+**Last Updated**: August 19, 2026
+**Claude Code Version**: 2.1.235
 **Sources**:
 - https://code.claude.com/docs/en/hooks
 - https://code.claude.com/docs/en/overview