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.

LEARNING-ROADMAP.md

@@ -102,7 +102,7 @@ graph TD
 | **3** | [Checkpoints](08-checkpoints/) | ⭐⭐ Intermediate | 45 min | Level 1 | Session management | Safe exploration | Experimentation, recovery |
 | **4** | [CLI Basics](10-cli/) | ⭐⭐ Beginner+ | 30 min | Level 1 | None | Core CLI usage | Interactive & print mode |
 | **5** | [Skills](03-skills/) | ⭐⭐ Intermediate | 1 hour | Level 2 | Slash Commands | Automatic expertise | Reusable capabilities, consistency |
-| **6** | [Hooks](06-hooks/) | ⭐⭐ Intermediate | 1 hour | Level 2 | Tools, Commands | Workflow automation (28 events, 5 types) | Validation, quality gates |
+| **6** | [Hooks](06-hooks/) | ⭐⭐ Intermediate | 1 hour | Level 2 | Tools, Commands | Workflow automation (29 events, 5 types) | Validation, quality gates |
 | **7** | [MCP](05-mcp/) | ⭐⭐⭐ Intermediate+ | 1 hour | Level 2 | Configuration | Live data access | Real-time integration, APIs |
 | **8** | [Subagents](04-subagents/) | ⭐⭐⭐ Intermediate+ | 1.5 hours | Level 2 | Memory, Commands | Complex task handling (6 built-in including Bash) | Delegation, specialized expertise |
 | **9** | [Advanced Features](09-advanced-features/) | ⭐⭐⭐⭐⭐ Advanced | 2-3 hours | Level 3 | All previous | Power user tools | Planning, Auto Mode, Channels, Voice Dictation, permissions |
@@ -235,7 +235,7 @@ Before starting Level 2, make sure you're comfortable with these Level 1 concept
 
 #### What You'll Achieve
 ✅ Auto-invoke specialized capabilities with YAML frontmatter (including `effort` and `shell` fields)
-✅ Set up event-driven automation across 28 hook events
+✅ Set up event-driven automation across 29 hook events
 ✅ Use all 5 hook types (command, http, mcp_tool, prompt, agent)
 ✅ Enforce code quality standards
 ✅ Create custom hooks for your workflow
@@ -738,12 +738,13 @@ Once you've completed all milestones:
 
 ---
 
-**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/overview
 - https://code.claude.com/docs/en/hooks
 - 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
 **Maintained by**: Claude How-To Contributors
 **License**: Educational purposes, free to use and adapt