feat(frontend): scaffold Vue 3 + Vite + Tailwind Gruvbox

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

frontend/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "jsx": "preserve",
+    "lib": ["ES2020", "DOM"],
+    "skipLibCheck": true,
+    "paths": { "@/*": ["./src/*"] }
+  },
+  "include": ["src/**/*.ts", "src/**/*.vue"]
+}