chore: configure project with src/ directory structure and tooling

- Move app files into src/ directory following Next.js convention
- Add baseUrl: src/ to tsconfig.json for path resolution
- Add .vscode/launch.json with debug configs for dev/build/start/lint
- Add lint:fix npm script to package.json

package.json

@@ -6,7 +6,8 @@
     "dev": "next dev",
     "build": "next build",
     "start": "next start",
-    "lint": "eslint"
+    "lint": "eslint",
+    "lint:fix": "eslint --fix"
   },
   "dependencies": {
     "next": "16.2.7",