Implement Excerpt Generator for Word Content and Use in SEO Meta Description

Currently, each word's content in the Astro project lacks a meta description, which is crucial for search engine optimization (SEO) and improving discoverability. To enhance this, we should implement an excerpt generator that extracts a concise summary from each word's content and uses it as the meta description value.

#### Task
1. **Excerpt Generation**:
- Implement a function or logic to generate a concise excerpt from the content of each word in the Astro project.

2. **Integration with Meta Description**:
- Update the `word.astro` layout to utilize the generated excerpt as the meta description.

#### Implementation Steps
1. **Excerpt Logic**:
- Develop a method to extract a summary or snippet from the content of each word.
- Consider factors such as length, readability, and relevance to ensure the excerpt effectively summarizes the content.

2. **Meta Description Integration**:
- Modify the `word.astro` layout to incorporate the generated excerpt as the meta description tag.

#### Acceptance Criteria
- Each word's content should have a dynamically generated excerpt.
- The generated excerpt should be integrated into the `word.astro` layout as the meta description.

#### Additional Information
Implementing an excerpt generator will improve SEO by providing meaningful meta descriptions for each word's page, aiding in better search engine ranking and user engagement.

まず、Astroプロジェクトのword.astroレイアウトと単語コンテンツの構造を読んでください。抜粋をどのように生成できるか、また適切な長さとフォーマットは何かを判断し、そのうえで各単語ページが生成された抜粋をmeta descriptionとして公開していることを確認してください。

索引モデルが issue の本文から書いたものです。