feat(study): 공부 암기노트 Phase 1 — card_extract 추출 파이프라인 (순수 additive)

study_memo_cards 추출 파이프라인 + 버전키 폴러 + needs_review 컬럼. 운영 SR 코드(session_finalize/quiz_selection) 무수정.

- migrations 287~298: study_memo_cards/_evidence/_jobs/_progress(P1 휴면)·study_reminders·study_topics.focused_at·study_questions needs_review 3컬럼. dedup PARTIAL UNIQUE(deleted_at IS NULL).
- 워커: in-process RAG gather → MLX {cards} → 카드 가드(정량=evidence 원문 등장·cue/cloze 누출·dedup) → supersede 구버전 retire → append. 별 consumer 로 기존 study_queue 격리.
- 폴러 study_card_enqueue: 버전키 NOT EXISTS(source_version) 멱등 + ai_explanation_generated_at NOT NULL 가드 + per-poll LIMIT(thundering-herd).
- 검증: 실 prod 스키마 덤프 위 12 마이그 적용 OK + dedup/supersede/active-unique 기능 7/7 PASS + 정규화 util 15/15.

plan: PKM plans/2026-06-05-study-memo-card-p1-plan.html

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/core/config.py

@@ -157,6 +157,8 @@ class Settings(BaseModel):
     # PR-MacMini-Derived-Worker-1: study explanation owner = Mac mini
     # GPU 측은 false 로 설정 (.env), explanation 분기 skip guard 트리거.
     study_explanation_enabled: bool = True
+    # 공부 암기노트 Phase 1: card_extract 폴러/consumer 게이트. owner 분리 시 false 로.
+    study_card_extract_enabled: bool = True
 
     # internal endpoint Bearer token (Mac mini derived-worker 호출용)
     internal_worker_token: str = ""
@@ -167,6 +169,7 @@ def load_settings() -> Settings:
     # 환경변수 (docker-compose에서 주입)
     database_url = os.getenv("DATABASE_URL", "")
     study_explanation_enabled = os.getenv("STUDY_EXPLANATION_ENABLED", "true").lower() in ("1", "true", "yes")
+    study_card_extract_enabled = os.getenv("STUDY_CARD_EXTRACT_ENABLED", "true").lower() in ("1", "true", "yes")
     internal_worker_token = os.getenv("INTERNAL_WORKER_TOKEN", "")
     jwt_secret = os.getenv("JWT_SECRET", "")
     totp_secret = os.getenv("TOTP_SECRET", "")
@@ -262,6 +265,7 @@ def load_settings() -> Settings:
         document_types=document_types,
         upload=upload_cfg,
         study_explanation_enabled=study_explanation_enabled,
+        study_card_extract_enabled=study_card_extract_enabled,
         internal_worker_token=internal_worker_token,
     )