feat: 이드 도구 확장 — 캘린더/메일/문서 연동 (read-only + 캘린더 생성 확인)

- tools/calendar_tool.py: CalDAV search/today/create_draft/create_confirmed
- tools/email_tool.py: IMAP search/read (전송 비활성화)
- tools/document_tool.py: Document Server search/read (read-only)
- tools/registry.py: 도구 디스패처 + WRITE_OPS 안전장치 + 에러 표준화
- 분류기: "tools" 액션 추가, 도구 목록/파라미터 스키마/규칙 명시
- Worker: tools 분기 + tool timeout 10초 + payload 2000자 제한
- conversation: pending_draft (TTL 5분) + create 확인 플로우
- 현재 시간을 분류기에 전달 (날짜 질문 대응)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nanoclaude/config.py

@@ -30,6 +30,21 @@ class Settings(BaseSettings):
     # DB
     db_path: str = "/app/data/nanoclaude.db"
 
+    # Calendar (CalDAV)
+    caldav_url: str = ""
+    caldav_user: str = ""
+    caldav_pass: str = ""
+
+    # MailPlus (read-only)
+    mailplus_host: str = ""
+    mailplus_port: int = 993
+    mailplus_user: str = ""
+    mailplus_pass: str = ""
+
+    # Document Server (read-only)
+    document_api_url: str = ""
+    document_api_token: str = ""
+
     # Synology Chat (비어있으면 비활성화)
     synology_incoming_url: str = ""
     synology_outgoing_token: str = ""