Ollama's OpenAI-compatible API mishandles anyOf[X, null] parameter
schemas. update_wiki_page (content/title/tags/description) and
smart_create_wiki_page (path) now use empty-string/empty-list
sentinels translated to None inside the tool, following the
biographer pattern from 9d7ce39.
Adds a snapshot test that walks every registered librarian tool's
emitted JSON schema and fails on any anyOf[..., null].
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>