Implement reconnect, idle reporting, and security hardening

src/lazy_enter/config.py

@@ -25,3 +25,26 @@ class Config:
     # Buffer
     output_buffer_interval: float = float(os.getenv("OUTPUT_BUFFER_INTERVAL", "2.0"))
     max_message_length: int = int(os.getenv("MAX_MESSAGE_LENGTH", "3000"))
+
+    # Status reporting / reconnect
+    reconnect_delay_seconds: float = float(os.getenv("RECONNECT_DELAY_SECONDS", "5.0"))
+    output_idle_report_seconds: int = int(
+        os.getenv("OUTPUT_IDLE_REPORT_SECONDS", "120")
+    )
+    input_idle_report_seconds: int = int(os.getenv("INPUT_IDLE_REPORT_SECONDS", "300"))
+
+    def validate_required_settings(self) -> None:
+        """필수 설정값 누락 여부를 검증한다."""
+        missing: list[str] = []
+        if not self.slack_bot_token:
+            missing.append("SLACK_BOT_TOKEN")
+        if not self.slack_app_token:
+            missing.append("SLACK_APP_TOKEN")
+        if not self.allowed_user_id:
+            missing.append("SLACK_ALLOWED_USER_ID")
+        if not self.allowed_channel_id:
+            missing.append("SLACK_ALLOWED_CHANNEL_ID")
+
+        if missing:
+            joined = ", ".join(missing)
+            raise ValueError(f"필수 환경 변수가 누락되었습니다: {joined}")