Rate limit waits in the response body

Notion's API now puts rate-limit wait times in the response body, so clients that can't read headers, including MCP clients, can see how long to wait.

Any 429 or 529 response with a Retry-After header repeats the wait in additional_data.retry_after. New rate_limit_reason values distinguish an endpoint's own limit, public_api_endpoint_rate_limit, from restricted connection access, public_api_request_blocked. A workspace-limit 429 also now explains that the limit is shared across all of the workspace's connections.