Scaffold project foundation

Fresh start: Vite + React 19 + strict TS, Tailwind v4, PWA, Vitest/Playwright.
Replaces the prior DeepSeek-built app (deleted; ~135 documented bugs, no VCS).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tsconfig.node.json

@@ -0,0 +1,18 @@
+{
+  "compilerOptions": {
+    "target": "ES2023",
+    "lib": ["ES2023"],
+    "module": "ESNext",
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "types": ["node"]
+  },
+  "include": ["vite.config.ts", "scripts/**/*.ts"]
+}