Add Vercel configuration for SPA routing; update base path in vite.config.ts and remove 404.html

Author: RumPumpumpum

public/404.html

@@ -0,0 +1,8 @@
+{
+	"rewrites": [
+		{
+			"source": "/(.*)",
+			"destination": "/"
+		}
+	]
+}

vercel.json

@@ -12,5 +12,5 @@ export default defineConfig({
 		}),
 		tailwindcss(),
 	],
-	base: process.env.NODE_ENV === "production" ? "/FE7-PROJECT2-TEAM-5/" : "/",
+	base: "/",
 });