Fetch and use Botkube website and docs for AI assistant

[pkosiec]

Description

Changes proposed in this pull request:

• Fetch Botkube website and docs for AI assistant
• Use Botkube website and docs for AI assistant
• Add Readme for assistant setup
• Migrate assistant setup to TypeScript
  • we need to use beta functionality (vertex store, file search) which isn't available in the unofficial Go client.

NOTE: While the LLM was instructed to use Botkube docs as much as possible, it still hallucinates sometimes. That's why I didn't do the requirement "Add footnote to the AI response: response assumes you use the latest Botkube" as I think "AI-generated content may be incorrect" is enough as it is right now.

I think the response quality will increase once we:

• split our documentation to two separate parts (directories/sections): Botkube self-hosted installation and Botkube Cloud
• add more examples for e.g. plugin configuration
• include plugin JSON schemas for configuration syntax?

Screenshots

Pretty close, but partially incorrect:

Related issue(s)

See https://github.com/kubeshop/botkube-cloud/issues/956

[mszostok]

I did a code review, the code LGTM 🚀 Tomorrow I can test that or we can just merge it to dev and test it there.

I only have a some concerns about overall process for fetching docs.

[pkosiec]

As agreed, I'll do a follow-up PR with:

• Add "purge" option for botkube.io/blog/* + botkube.io/learn/* in docs fetcher (disabled by default)
• Update release process in https://docs.botkube.io/community/contribute/release
  • Mention to release Botkube Cloud plugins every Botkube release (without details)
• Describe release process here in Readme: https://github.com/kubeshop/botkube-cloud-plugins?tab=readme-ov-file#release
  • Every Botkube Cloud plugins release will refetch all files and update assistant
• Update GitHub actions release job for Botkube Cloud plugins
  • Fetch docs and update AI assistant during release, with botkube.io/blog/* + botkube.io/learn/* purge disabled
• Fix vertex store deletion for different envs

Thanks @mszostok for feedback!