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>

manage_services.sh

@@ -6,8 +6,8 @@ SERVICES=(
   "com.syn-chat-bot.chat-bridge"
   "com.syn-chat-bot.heic-converter"
   "com.syn-chat-bot.caldav-bridge"
-  "com.syn-chat-bot.devonthink-bridge"
   "com.syn-chat-bot.kb-writer"
+  "com.syn-chat-bot.morning-briefing"
   "com.syn-chat-bot.mail-bridge"
   "com.syn-chat-bot.inbox-processor"
   "com.syn-chat-bot.news-digest"