docs: add native Japanese translation of ECC documentation (ja-JP)

Translate everything-claude-code repository to Japanese including:
- 17 root documentation files
- 60 agent documentation files
- 80 command documentation files
- 99 rule files across 18 language directories (common, angular, arkts, cpp, csharp, dart, fsharp, golang, java, kotlin, perl, php, python, ruby, rust, swift, typescript, web)
- 199 skill documentation files

Total: 455 files translated to Japanese with:
- Consistent terminology glossary applied throughout
- YAML field names preserved in English (name, description, etc.)
- Code blocks and examples untouched (comments translated)
- Markdown structure and relative links preserved
- Professional translation maintaining technical accuracy

This translation expands ECC accessibility to Japanese-speaking developers and teams.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

docs/ja-JP/rules/python/security.md

@@ -0,0 +1,30 @@
+---
+paths:
+  - "**/*.py"
+  - "**/*.pyi"
+---
+# Python セキュリティ
+
+> このファイルは [common/security.md](../common/security.md) を Python 固有のコンテンツで拡張します。
+
+## シークレット管理
+
+```python
+import os
+from dotenv import load_dotenv
+
+load_dotenv()
+
+api_key = os.environ["OPENAI_API_KEY"]  # 未設定の場合 KeyError を発生
+```
+
+## セキュリティスキャン
+
+- **bandit** を使用して静的セキュリティ解析を実行:
+  ```bash
+  bandit -r src/
+  ```
+
+## リファレンス
+
+スキル: `django-security` で Django 固有のセキュリティガイドラインを参照してください（該当する場合）。