Add Japanese translation: Core Feature Workshops Bundle

[gentksb]

Description

Add Japanese translations for Core Feature workshops:

• 7-dashboards-detectors (14 Markdown files)
• 2-hpa (9 Markdown files)
• 9-solving-problems-with-o11y-cloud (7 Markdown files)
• 11-ingest-processor-for-observability-cloud (13 Markdown files)
• 12-alerting-monitoring-with-itsi (10 Markdown files)
• 13-observing-business-journeys (1 Markdown file)

Total: 54 Markdown files + images = 203 files

Translation guidelines followed:

• Product names preserved (Splunk, ITSI, OpenTelemetry, Kubernetes, etc.)
• Code blocks, CLI commands, and URLs unchanged
• Japanese polite form (です/ます) used consistently
• Hugo shortcodes maintained as-is

Fixes # N/A (new translation)

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• Verified Japanese pages render correctly with hugo serve
• Checked navigation between translated pages
• Verified links and images work properly
• Compared with existing translations for style consistency

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Markdown Lint passes locally with my changes
• Any dependent changes have been merged and published in downstream modules

🤖 Generated with Claude Code

[gentksb]

To be review.
We are under defining the policy of AI generated workshop translation in Japan SA Team.

[knakagami]

# が入っていることで、質問分が大文字で表示されるようになっています。

[knakagami]

これは翻訳元ファイル自体の問題ですが、画像ファイルはリンク切れしていますね（ただ、ファイルパスは存在していそう）