Introduce four ORM models and their Alembic migration to support
phrase-based query matching in the ebook RAG engine:
- EbookCandidatePhrase: high-recall phrase candidates extracted per book,
with source flags (ngram/yake/spacy/capitalized/metadata), scoring, and
LLM judge results.
- EbookProtectedPhrase: phrases accepted by the LLM judge, with canonical
id, importance, and nesting controls.
- EbookPhraseAlias: normalized aliases mapping to protected phrases.
- EbookChunkPhraseMention: precomputed phrase occurrences within chunks.
Export the new models from python.orm.richie and add a JSON_DOCUMENT
helper (JSON with JSONB postgres variant) for storing sample contexts.
Richie