docs: remove 9 retired provider pages and references

[SannidhyaSah]

Summary

Remove documentation for the 9 providers retired in RooCodeInc/Roo-Code#11297:

Providers removed: Cerebras, Chutes, DeepInfra, Doubao, Featherless, Groq, Hugging Face, IO Intelligence, Unbound

Changes

• Delete 9 provider doc pages — cerebras, chutes, deepinfra, doubao, featherless, groq, huggingface, io-intelligence, unbound
• Update docs/providers/index.json — remove all 9 provider entries from the sidebar
• Update docs/features/intelligent-context-condensing.mdx — remove Cerebras from error detection provider list
• Add redirects in docusaurus.config.ts — redirect all 9 deleted provider URLs to /
• Fix broken links in historical update-notes — convert provider links to plain text or retired notices to keep build clean

Verification

• Build passes with zero warnings
• No remaining broken links to deleted provider pages

---

Important

Remove documentation and references for 9 retired providers, add redirects, and fix links to ensure a clean build.

• Documentation Removal:
  • Delete documentation pages for 9 retired providers: Cerebras, Chutes, DeepInfra, Doubao, Featherless, Groq, Hugging Face, IO Intelligence, Unbound.
  • Remove references to these providers in index.json and intelligent-context-condensing.mdx.
• Redirects:
  • Add redirects in docusaurus.config.ts for deleted provider URLs to root.
• Link Fixes:
  • Convert links to plain text or retired notices in historical update notes to prevent build warnings.

^{This description was created by for f9c7eac. You can customize this summary. It will automatically update as commits are pushed.}

[vercel]

Someone is attempting to deploy a commit to the Roo Code Team on Vercel.

A member of the Team first needs to authorize it.

[vercel]

Someone is attempting to deploy a commit to the Roo Code Team on Vercel.

A member of the Team first needs to authorize it.

[vercel]

Someone is attempting to deploy a commit to the Roo Code Team on Vercel.

A member of the Team first needs to authorize it.