v0.0.19 | Internet Gateway / Routing Table 관리 API 추가

- ApiVpc에 IGW CRUD 추가 (/v2.0/internetgateways, external_network_id 사용)
- IGW/RoutingTable/Subnet-attach View 및 URL 신규 (모두 동기)
- API_SPEC.md 3.7.1~3.7.8 네트워크 섹션 추가

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nhn/packages/vpc.py

@@ -196,6 +196,46 @@ class ApiVpc(BaseAPI):
         payload = {"routingtable_id": routingtable_id}
         return self._put(url, payload)
 
+    # ==================== Internet Gateway ====================
+
+    def get_internet_gateway_list(self) -> dict:
+        """인터넷 게이트웨이 목록 조회"""
+        url = f"{self.vpc_url}/v2.0/internetgateways"
+        logger.info(f"[NHN API] IGW 목록 조회 요청 - URL={url}")
+        result = self._get(url)
+        count = len(result.get("internetgateways", []))
+        logger.info(f"[NHN API] IGW 목록 조회 완료 - count={count}")
+        return result
+
+    def get_internet_gateway_info(self, internetgateway_id: str) -> dict:
+        """인터넷 게이트웨이 상세 조회"""
+        url = f"{self.vpc_url}/v2.0/internetgateways/{internetgateway_id}"
+        return self._get(url)
+
+    def create_internet_gateway(self, name: str, external_network_id: str) -> dict:
+        """
+        인터넷 게이트웨이 생성
+
+        Args:
+            name: IGW 이름
+            external_network_id: 외부 네트워크 ID (get_external_network_id 로 조회)
+        """
+        url = f"{self.vpc_url}/v2.0/internetgateways"
+        payload = {
+            "internetgateway": {
+                "name": name,
+                "external_network_id": external_network_id,
+            }
+        }
+        logger.info(f"IGW 생성 요청: {name} (external_network={external_network_id})")
+        return self._post(url, payload)
+
+    def delete_internet_gateway(self, internetgateway_id: str) -> dict:
+        """인터넷 게이트웨이 삭제"""
+        url = f"{self.vpc_url}/v2.0/internetgateways/{internetgateway_id}"
+        logger.info(f"IGW 삭제 요청: {internetgateway_id}")
+        return self._delete(url)
+
     # ==================== Floating IP ====================
 
     def get_external_network_id(self) -> dict: