feat(i18n): Add Japanese (ja/) translation (#105)

- Translate all 101 markdown files: P1 core, all 10 modules, examples,
  auxiliary docs (CONTRIBUTING, CODE_OF_CONDUCT, SECURITY, CLAUDE.md, etc.),
  peripheral docs (.github/, docs/, resources/, scripts/)
- Translate comments and user-facing messages in 06-hooks/*.sh examples
- Copy 05-mcp/*.json examples (standard JSON, no comments)
- Update root README.md language switcher to include 日本語
- Add ja/TRANSLATION_NOTES.md (glossary + style guide)

All translations pass pre-commit quality gates (markdown-lint,
cross-references, mermaid-syntax, link-check, build-epub).

ja/07-plugins/devops-automation/agents/incident-commander.md

@@ -0,0 +1,18 @@
+<!-- i18n-source: 07-plugins/devops-automation/agents/incident-commander.md -->
+<!-- i18n-source-sha: 5caeff2 -->
+<!-- i18n-date: 2026-04-27 -->
+
+---
+name: incident-commander
+description: インシデントレスポンスを統括する
+tools: read, write, bash, grep
+---
+
+# Incident Commander
+
+インシデントレスポンスを管理する：
+- 重大度の評価
+- チーム調整
+- ステータス更新
+- 解決状況の追跡
+- ポストモーテムの取りまとめ