enhance(dev): frontendの検索インデックス作成を単独のコマンドで行えるように

[kakkokari-gtyih]

What

pnpm build-frontend-search-index で、開発サーバーを起動することなく検索インデックスの再生成を行えるように

Why

Fix #15648

Additional info (optional)

pnpm build-assets でできるようにするのでもいいかもしれない

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests

[codecov]

Codecov Report

Attention: Patch coverage is 3.84615% with 25 lines in your changes missing coverage. Please review.

Project coverage is 15.30%. Comparing base (d185785) to head (d1b0fb2).
Report is 8 commits behind head on develop.

Files with missing lines	Patch %	Lines
...es/frontend/lib/vite-plugin-create-search-index.ts	0.00%	15 Missing ⚠️
packages/frontend/scripts/generate-search-index.ts	11.11%	8 Missing ⚠️
packages/frontend/vite-node.config.ts	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           develop   #15653       +/-   ##
============================================
- Coverage    41.87%   15.30%   -26.57%     
============================================
  Files         1625      788      -837     
  Lines       166074    72504    -93570     
  Branches      4108     1280     -2828     
============================================
- Hits         69537    11095    -58442     
+ Misses       96093    60983    -35110     
+ Partials       444      426       -18     

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[syuilo]

🙏🏻