feat: DEVONthink 제거 + 모닝 브리핑 추가

- DEVONthink 의존성 제거 → kb_writer 전환 (news_digest, inbox_processor, mail pipeline)
- devonthink_bridge.py, plist 삭제
- morning_briefing.py 신규 (매일 07:30, 일정·메일·보고·뉴스 → Synology Chat)
- intent_service.py 분류기 프롬프트 개선 + 키워드 fallback
- migrate-v5.sql (news_digest_log kb_path 컬럼)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -31,7 +31,6 @@ services:
       - HEIC_CONVERTER_URL=http://host.docker.internal:8090
       - CHAT_BRIDGE_URL=http://host.docker.internal:8091
       - CALDAV_BRIDGE_URL=http://host.docker.internal:8092
-      - DEVONTHINK_BRIDGE_URL=http://host.docker.internal:8093
       - MAIL_BRIDGE_URL=http://host.docker.internal:8094
       - KB_WRITER_URL=http://host.docker.internal:8095
       - NODE_FUNCTION_ALLOW_BUILTIN=crypto,http,https,url