docs(ja-JP): translate plain text code blocks to Japanese

Translate English prose inside plain text code blocks (```text, ```)
across ja-JP documentation to Japanese, following the same approach
as PR #753 (zh-CN translation).

Translated content includes:
- Output template labels and status messages
- Folder tree inline comments
- CLI workflow descriptions
- Error/warning message examples
- Commit message templates and PR title examples

Technical identifiers, file paths, and actual code remain untranslated.

docs/ja-JP/skills/golang-patterns/SKILL.md

@@ -368,17 +368,17 @@ func WriteAndFlush(w io.Writer, data []byte) error {
 myproject/
 ├── cmd/
 │   └── myapp/
-│       └── main.go           # Entry point
+│       └── main.go           # エントリポイント
 ├── internal/
-│   ├── handler/              # HTTP handlers
-│   ├── service/              # Business logic
-│   ├── repository/           # Data access
-│   └── config/               # Configuration
+│   ├── handler/              # HTTP ハンドラー
+│   ├── service/              # ビジネスロジック
+│   ├── repository/           # データアクセス
+│   └── config/               # 設定
 ├── pkg/
-│   └── client/               # Public API client
+│   └── client/               # 公開 API クライアント
 ├── api/
-│   └── v1/                   # API definitions (proto, OpenAPI)
-├── testdata/                 # Test fixtures
+│   └── v1/                   # API 定義（proto、OpenAPI）
+├── testdata/                 # テストフィクスチャ
 ├── go.mod
 ├── go.sum
 └── Makefile