Add deprecation note

[brillout]

Follow up of cloudflare/workers-sdk#10121.

Hi @Aslemammad, since this project doesn't seem to be actively developed anymore and Cloudflare is developing @cloudflare/vite-plugin, how about we add a deprecation warning and redirect users to @cloudflare/vite-plugin?

Quoting @jamesopstad from the Cloudflare team:

Hi. Thanks a lot for the offer of passing on the vite-plugin-cloudflare package! Really appreciate it.

I don't think we would publish to this name as we would like to keep @cloudflare/vite-plugin under the Cloudflare namespace. Would you be happy to instead update the README for vite-plugin-cloudflare so that it marks it as archived/deprecated and directs users to @cloudflare/vite-plugin?