fix(build): resolve vue-tsc -b build errors — add @types/node, fix tsconfig emit settings

The production build (vue-tsc -b) failed because tsconfig.node.json had
allowImportingTsExtensions without a compatible emit setting, and @types/node
was missing for node:url imports in vite.config.ts.

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

.gitignore

@@ -4,3 +4,7 @@ __pycache__/
 .venv/
 node_modules/
 dist/
+*.tsbuildinfo
+*.d.ts
+!src/**/*.d.ts
+frontend/vite.config.js

frontend/package-lock.json

@@ -16,6 +16,7 @@
       },
       "devDependencies": {
         "@types/d3": "^7.4.0",
+        "@types/node": "^25.5.0",
         "@vitejs/plugin-vue": "^5.1.0",
         "typescript": "~5.6.0",
         "vite": "^6.0.0",
@@ -1164,6 +1165,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/node": {
+      "version": "25.5.0",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-25.5.0.tgz",
+      "integrity": "sha512-jp2P3tQMSxWugkCUKLRPVUpGaL5MVFwF8RDuSRztfwgN1wmqJeMSbKlnEtQqU8UrhTmzEmZdu2I6v2dpp7XIxw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "undici-types": "~7.18.0"
+      }
+    },
     "node_modules/@vitejs/plugin-vue": {
       "version": "5.2.4",
       "resolved": "https://registry.npmjs.org/@vitejs/plugin-vue/-/plugin-vue-5.2.4.tgz",
@@ -2437,6 +2448,13 @@
         "node": ">=14.17"
       }
     },
+    "node_modules/undici-types": {
+      "version": "7.18.2",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.18.2.tgz",
+      "integrity": "sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/vite": {
       "version": "6.4.1",
       "resolved": "https://registry.npmjs.org/vite/-/vite-6.4.1.tgz",

frontend/package.json

@@ -17,6 +17,7 @@
   },
   "devDependencies": {
     "@types/d3": "^7.4.0",
+    "@types/node": "^25.5.0",
     "@vitejs/plugin-vue": "^5.1.0",
     "typescript": "~5.6.0",
     "vite": "^6.0.0",

frontend/tsconfig.node.json

@@ -4,9 +4,12 @@
     "module": "ESNext",
     "moduleResolution": "bundler",
     "allowImportingTsExtensions": true,
+    "emitDeclarationOnly": true,
+    "declaration": true,
     "strict": true,
     "composite": true,
-    "skipLibCheck": true
+    "skipLibCheck": true,
+    "types": ["node"]
   },
   "include": ["vite.config.ts"]
 }