optionally deploy firecrawl

for web crawling

references:

* https://github.com/mendableai/firecrawl
* https://qiita.com/hara2dev/items/a04b9724de9e7a1d4867#firecrawl%E3%82%92%E3%83%AD%E3%83%BC%E3%82%AB%E3%83%AB%E7%92%B0%E5%A2%83%E5%86%85%E3%81%A7%E4%BD%BF%E7%94%A8%E3%81%99%E3%82%8B

Start by reviewing the Firecrawl repository and the linked Qiita instructions for running Firecrawl locally. Determine how optional deployment for web crawling should fit this AWS-hosted Dify project; done should mean the deployment is optional and usable for crawling.

Written by the indexing model from the issue text.