feat: Sub-Phase 8.0 — config & enums for Q&A-pair chunking strategy
Backend:
- Add 6 Q&A chunking config fields to Settings (default_chunking_strategy,
qa_vision_enabled, qa_max_chunk_tokens, qa_structure_model,
qa_include_internal_refs, qa_cache_vision_results)
- Define ChunkingStrategyType Literal + VALID_CHUNKING_STRATEGIES frozenset
- Add strategy field to IngestResponse (default token, non-breaking)
- Add IngestRequest model with strategy param
- Update .env.example with new env vars
Frontend:
- Add ChunkingStrategy type ('token' | 'question')
- Extend IngestResponse, DocumentInfo, ChunkInfo with Q&A fields
Tests:
- test_qa_chunking_config_defaults — all defaults verified
- test_qa_chunking_config_from_env — env var overrides verified
Plan fix: renamed qa_verification_model → qa_structure_model to match
LLM-first architecture