🚚(frontend) delete useless nesting

Update frontend to be the root folder of the frontend sources,
instead of nesting them in a folder named as the application.

We only work on a single frontend app as of today, nesting
sources doesn't add any value, even though the initial organization
was more extensible.

src/frontend/tsconfig.node.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "composite": true,
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.node.tsbuildinfo",
+    "skipLibCheck": true,
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "noEmit": true
+  },
+  "include": ["vite.config.ts"]
+}