feat(chunk): Phase 0.1 chunk 인덱싱 — ORM/worker/migration 정리

GPU 서버에 untracked로만 존재하던 Phase 0.1 코드를 정식 commit:
- app/models/chunk.py — DocumentChunk ORM (country/source/domain 메타 포함)
- app/workers/chunk_worker.py — 6가지 chunking 전략 (legal/news/markdown/email/long_pdf/default)
- migrations/014_document_chunks.sql — pgvector + FTS + trigram 인덱스
- app/models/queue.py — ProcessingQueue enum에 'chunk' stage 추가
- app/workers/queue_consumer.py — chunk stage 등록, classify→[embed,chunk] 자동 연결

Phase 1 reranker 통합 작업의 전제 조건. document_chunks 테이블 기반 retrieval에 사용.

app/workers/queue_consumer.py

@@ -11,7 +11,7 @@ from models.queue import ProcessingQueue
 logger = setup_logger("queue_consumer")
 
 # stage별 배치 크기
-BATCH_SIZE = {"extract": 5, "classify": 3, "summarize": 3, "embed": 1, "preview": 2}
+BATCH_SIZE = {"extract": 5, "classify": 3, "summarize": 3, "embed": 1, "chunk": 1, "preview": 2}
 STALE_THRESHOLD_MINUTES = 10
 
 
@@ -34,7 +34,7 @@ async def reset_stale_items():
 
 async def enqueue_next_stage(document_id: int, current_stage: str):
     """현재 stage 완료 후 다음 stage를 pending으로 등록"""
-    next_stages = {"extract": ["classify", "preview"], "classify": ["embed"]}
+    next_stages = {"extract": ["classify", "preview"], "classify": ["embed", "chunk"]}
     stages = next_stages.get(current_stage, [])
     if not stages:
         return
@@ -62,6 +62,7 @@ async def enqueue_next_stage(document_id: int, current_stage: str):
 async def consume_queue():
     """큐에서 pending 항목을 가져와 stage별 워커 실행"""
     from workers.classify_worker import process as classify_process
+    from workers.chunk_worker import process as chunk_process
     from workers.embed_worker import process as embed_process
     from workers.extract_worker import process as extract_process
     from workers.preview_worker import process as preview_process
@@ -72,6 +73,7 @@ async def consume_queue():
         "classify": classify_process,
         "summarize": summarize_process,
         "embed": embed_process,
+        "chunk": chunk_process,
         "preview": preview_process,
     }