refactor: migrate to Next.js with edge functions and update relay utilities

- Removed old relay utilities and tests, replacing them with a new structure under `src/lib/relay-utils.ts`.
- Implemented a new edge function in `app/api/proxy/route.ts` to handle proxy requests.
- Created a new Next.js layout and page structure for the frontend, including a user interface for testing the proxy.
- Added Tailwind CSS for styling and configured PostCSS.
- Updated TypeScript configuration for better compatibility with Next.js.
- Removed unused files and configurations related to the previous setup.

vercel.json

@@ -1,17 +0,0 @@
-{
-	"$schema": "https://openapi.vercel.sh/vercel.json",
-	"bunVersion": "1",
-	"installCommand": "bun install",
-	"outputDirectory": "dist",
-	"trailingSlash": false,
-	"rewrites": [
-		{
-			"source": "/api",
-			"destination": "/api/index.ts"
-		},
-		{
-			"source": "/api/(.*)",
-			"destination": "/api/index.ts"
-		}
-	]
-}