Improve error message for uv init already init-ed (#7198)
Someone in
https://discord.com/channels/1039017663004942429/1207998321562619954/1282411049106145400
found this confusing
Could maybe improve further, e.g. what the user should do next might
depend if there are [project] or [tool.uv] sections
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Co-authored-by: Charlie Marsh <crmarsh416@gmail.com>
