지도 마커 클러스터링 적용 (supercluster)

- 줌 16 이하에서 근접 마커를 숫자 원형 클러스터로 묶음
- 클러스터 클릭 시 해당 영역으로 자동 줌인
- 개별 마커 스타일/채널 색상 유지

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

frontend/package-lock.json

@@ -9,10 +9,12 @@
       "version": "0.1.0",
       "dependencies": {
         "@react-oauth/google": "^0.13.4",
+        "@types/supercluster": "^7.1.3",
         "@vis.gl/react-google-maps": "^1.7.1",
         "next": "16.1.6",
         "react": "19.2.3",
-        "react-dom": "19.2.3"
+        "react-dom": "19.2.3",
+        "supercluster": "^8.0.1"
       },
       "devDependencies": {
         "@tailwindcss/postcss": "^4",
@@ -1544,6 +1546,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/geojson": {
+      "version": "7946.0.16",
+      "resolved": "https://registry.npmjs.org/@types/geojson/-/geojson-7946.0.16.tgz",
+      "integrity": "sha512-6C8nqWur3j98U6+lXDfTUWIfgvZU+EumvpHKcYjujKH7woYyLj2sUmff0tRhrqM7BohUw7Pz3ZB1jj2gW9Fvmg==",
+      "license": "MIT"
+    },
     "node_modules/@types/google.maps": {
       "version": "3.58.1",
       "resolved": "https://registry.npmjs.org/@types/google.maps/-/google.maps-3.58.1.tgz",
@@ -1595,6 +1603,15 @@
         "@types/react": "^19.2.0"
       }
     },
+    "node_modules/@types/supercluster": {
+      "version": "7.1.3",
+      "resolved": "https://registry.npmjs.org/@types/supercluster/-/supercluster-7.1.3.tgz",
+      "integrity": "sha512-Z0pOY34GDFl3Q6hUFYf3HkTwKEE02e7QgtJppBt+beEAxnyOpJua+voGFvxINBHa06GwLFFym7gRPY2SiKIfIA==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/geojson": "*"
+      }
+    },
     "node_modules/@typescript-eslint/eslint-plugin": {
       "version": "8.56.1",
       "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.56.1.tgz",
@@ -4555,6 +4572,12 @@
         "node": ">=4.0"
       }
     },
+    "node_modules/kdbush": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/kdbush/-/kdbush-4.0.2.tgz",
+      "integrity": "sha512-WbCVYJ27Sz8zi9Q7Q0xHC+05iwkm3Znipc2XTlrnJbsHMYktW4hPhXUE8Ys1engBrvffoSCqbil1JQAa7clRpA==",
+      "license": "ISC"
+    },
     "node_modules/keyv": {
       "version": "4.5.4",
       "resolved": "https://registry.npmjs.org/keyv/-/keyv-4.5.4.tgz",
@@ -6086,6 +6109,15 @@
         }
       }
     },
+    "node_modules/supercluster": {
+      "version": "8.0.1",
+      "resolved": "https://registry.npmjs.org/supercluster/-/supercluster-8.0.1.tgz",
+      "integrity": "sha512-IiOea5kJ9iqzD2t7QJq/cREyLHTtSmUT6gQsweojg9WH2sYJqZK9SswTu6jrscO6D1G5v5vYZ9ru/eq85lXeZQ==",
+      "license": "ISC",
+      "dependencies": {
+        "kdbush": "^4.0.2"
+      }
+    },
     "node_modules/supports-color": {
       "version": "7.2.0",
       "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",