6a5424a618
Implements QuestionGenStore with:
- Idempotent schema initialization (question_gen_runs + question_gen_items)
- Run lifecycle: record_run_start / record_run_end / get_run_stats
- Per-item recording: record_item / update_gates / update_difficulty
- GateReportLike Protocol for duck-type gate report compatibility
- WAL mode + foreign keys + check_same_thread=False
DDL aligns with research-wiki/schemas/question-gen-{runs,items}.md.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>