add web demo

apps/web/app/api/upload/route.ts

@@ -0,0 +1,31 @@
+import { put } from "@vercel/blob";
+import { NextResponse } from "next/server";
+
+export const runtime = "edge";
+
+export async function POST(req: Request) {
+  if (!process.env.BLOB_READ_WRITE_TOKEN) {
+    return new Response(
+      "Missing BLOB_READ_WRITE_TOKEN. Don't forget to add that to your .env file.",
+      {
+        status: 401,
+      },
+    );
+  }
+
+  const file = req.body || "";
+  const filename = req.headers.get("x-vercel-filename") || "file.txt";
+  const contentType = req.headers.get("content-type") || "text/plain";
+  const fileType = `.${contentType.split("/")[1]}`;
+
+  // construct final filename based on content-type if not provided
+  const finalName = filename.includes(fileType)
+    ? filename
+    : `${filename}${fileType}`;
+  const blob = await put(finalName, file, {
+    contentType,
+    access: "public",
+  });
+
+  return NextResponse.json(blob);
+}