#230 docs(api-reference): remove legacy POST /api/chat streaming endpoint

Removes the legacy POST /api/chat streaming endpoint from the docs, matching its removal from the API (recoupable/api#632). The current streaming surface is POST /api/chat/workflow.

• Drops the /api/chat path + ChatStreamRequest schema from research.json (keeps ChatStreamErrorResponse, still used by /api/chat/workflow)
• Deletes api-reference/chat/stream.mdx and its nav entry
• Repoints dead chat/stream links in credits.mdx to /api/chat/workflow

⚠️ Merge alongside recoupable/api#632 (after chat#1765).

Test plan

• research.json and docs.json parse as valid JSON
• No remaining links to chat/stream
• Mintlify preview renders the Chat group without the Stream page

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Summary by cubic

Removes the legacy POST /api/chat streaming endpoint from the docs and consolidates streaming under POST /api/chat/workflow. Cleans up dead links and matches the current API.

• Refactors

  • Dropped /api/chat path and ChatStreamRequest from api-reference/openapi/research.json (kept ChatStreamErrorResponse for workflow).
  • Deleted api-reference/chat/stream.mdx and removed its nav entry in docs.json.
  • Updated credits.mdx links to /api/chat/workflow and removed the “Parallel to POST /api/chat” note in the workflow description.

• Migration

  • Use POST /api/chat/workflow for streaming.