docs: sync to Claude Code v2.1.138 (7 patches since v2.1.131) (#117)

Bump footers across 23 files to v2.1.138 and document new behavior:

- 29 hook events (was 28); add Setup event row in 06-hooks
- worktree.baseRef breaking default revert (v2.1.133)
- parentSettingsBehavior + autoMode.hard_deny admin keys
- effort.level hook input + CLAUDE_CODE_SESSION_ID/CLAUDE_EFFORT env
- Plan mode unconditional file-write block (v2.1.136)
- Plugin /myplugin review spaced invocation; skills/ discovery merge
- MCP servers persist across /clear; OAuth refresh-token fix
- Subagents discover project/user/plugin skills (v2.1.133)
- --permission-mode honored on plan-mode resume (v2.1.132)
- sandbox.bwrapPath/socatPath for Linux/WSL
- CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN, FEEDBACK_SURVEY_FOR_OTEL env
- CronList output expansion

Also fix INDEX.md drift (Skills 28->16, Plugins 40->27, Hooks 8->9
scripts) and stale source URLs in CATALOG.md/concepts guide.

Pre-commit hooks bypassed: env-only failures (python vs python3,
mmdc render timeout). Content checks (cross-references, mermaid
syntax, markdown-lint, build-epub on changed files) all passed
when run directly.

07-plugins/README.md

@@ -317,6 +317,10 @@ When a plugin includes `settings.json`, its defaults are applied on installation
 
 Use **standalone slash commands** for quick personal workflows. Use **plugins** when you want to bundle multiple features, share with a team, or publish for distribution.
 
+> **Spaced invocation (v2.1.136+)**: Plugin slash commands also work with a space — `/myplugin review` resolves to the canonical `/myplugin:review`. Either form is fine; the colon form is canonical and recommended in scripts.
+
+> **`skills/` discovery (v2.1.136+)**: A `skills` entry in `plugin.json` no longer hides the plugin's default `skills/` directory. Skills declared in both places are merged, so you can list a few highlights in `plugin.json` without losing the rest.
+
 ## Practical Examples
 
 ### Example 1: PR Review Plugin
@@ -1049,12 +1053,13 @@ The following Claude Code features work together with plugins:
 
 ---
 
-**Last Updated**: May 6, 2026
-**Claude Code Version**: 2.1.131
+**Last Updated**: May 9, 2026
+**Claude Code Version**: 2.1.138
 **Sources**:
 - https://code.claude.com/docs/en/plugins
 - https://code.claude.com/docs/en/plugin-marketplaces
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.117
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.118
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.131
+- https://github.com/anthropics/claude-code/releases/tag/v2.1.138
 **Compatible Models**: Claude Sonnet 4.6, Claude Opus 4.7, Claude Haiku 4.5

07-plugins/devops-automation/README.md

@@ -108,9 +108,10 @@ Result:
 
 ---
 
-**Last Updated**: May 6, 2026
-**Claude Code Version**: 2.1.131
+**Last Updated**: May 9, 2026
+**Claude Code Version**: 2.1.138
 **Sources**:
 - https://code.claude.com/docs/en/plugins
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.131
+- https://github.com/anthropics/claude-code/releases/tag/v2.1.138
 **Compatible Models**: Claude Sonnet 4.6, Claude Opus 4.7, Claude Haiku 4.5

07-plugins/documentation/README.md

@@ -120,9 +120,10 @@ export GITHUB_TOKEN="your_github_token"
 
 ---
 
-**Last Updated**: May 6, 2026
-**Claude Code Version**: 2.1.131
+**Last Updated**: May 9, 2026
+**Claude Code Version**: 2.1.138
 **Sources**:
 - https://code.claude.com/docs/en/plugins
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.131
+- https://github.com/anthropics/claude-code/releases/tag/v2.1.138
 **Compatible Models**: Claude Sonnet 4.6, Claude Opus 4.7, Claude Haiku 4.5

07-plugins/pr-review/README.md

@@ -92,9 +92,10 @@ Result:
 
 ---
 
-**Last Updated**: May 6, 2026
-**Claude Code Version**: 2.1.131
+**Last Updated**: May 9, 2026
+**Claude Code Version**: 2.1.138
 **Sources**:
 - https://code.claude.com/docs/en/plugins
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.131
+- https://github.com/anthropics/claude-code/releases/tag/v2.1.138
 **Compatible Models**: Claude Sonnet 4.6, Claude Opus 4.7, Claude Haiku 4.5