-- 2026-05-24 PR-Chore-OCR-Column-1 (1/2): documents.ocr_derived boolean 컬럼 추가.
-- RAG-independent data hygiene. ocr_derived 식별 컬럼 부재 = PR-Eval-V0_2 TBD-O FAILED 원인.
-- backfill 은 278 별 migration (asyncpg single-statement 제약).
ALTER TABLE documents ADD COLUMN IF NOT EXISTS ocr_derived boolean DEFAULT false NOT NULL;