Align Knowledge endpoints in 2.17 and Preview with API responses

Correct the internal article, folder, content snippet, content search and
bulk action operations so the spec matches what the API returns.

- Add the OAuth scope line to the operations that lacked one
- Document the real error responses (401 token scope, 400 and 422
  validation, 404 unknown teammate or folder, live-experiment conflict)
  and fix examples whose codes or messages could not be produced
- Document page and per_page on list and search internal articles, the
  optional admin_id on tag removal, and the locale and json_blocks
  request fields
- Note that omitted keys (folder list fields, content search next and
  prev) are absent rather than null
- Regenerate the internal article update and search examples with every
  returned field, and drop the heading the markdown output never emits
- Add tags to the internal article list item (2.17) and widen the tag
  schema description to cover internal articles and content snippets

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: cathalging