Inject VITE_CLOUD_URL at runtime

[sunng87]

          We need to seek a further solution to inject `VITE_CLOUD_URL` at runtime so we can reuse same image across different environments. Let me create an issue for this.

Originally posted by @sunng87 in #156 (review)

[ZonaHex]

I don't think we could use the same image for dev and staging. Because the variable is determined during build-time.
We could edit the action YML and make sure the commit sha for the staging image is (one of) the latest sha for the dev image (already tested).
Perhaps add a new file to store the latest sha list. The commit sha for the staging image should only be selected from the sha list, not be text editable.