[Media Upload] Update error message to suggest Nostr.build

[setch-l]

Given that I am a user of Nos When I upload a file larger than 7 mb Then I should see an error message telling me about Nostr.build.

Use error message option 1. From this design file: https://www.figma.com/design/s0qf4VmyQygydP8MIQazZc/Nos?node-id=7027-28279&t=xSzfWfp6iOCeoXy8-1