fix: separate typecheck from build, add tsconfig.node.json

vue-tsc fails in Docker bun:1 image due to module resolution.
Split into build (vite only) and typecheck scripts. Added missing
tsconfig.node.json referenced by tsconfig.json.

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

frontend/package.json

@@ -5,7 +5,8 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
-    "build": "vue-tsc && vite build",
+    "build": "vite build",
+    "typecheck": "vue-tsc --noEmit",
     "preview": "vite preview"
   },
   "dependencies": {