Edits to the freshly generated project.

render_config/1 uses a heredoc rather than a formatter round-trip: nothing in the MVP re-reads svelixir.exs byte-for-byte, so a second encoder here would duplicate the hex package's codec with no mechanism keeping the two in step — and this archive ships zero dependencies, so it cannot call that codec. The root suite asserts the rendered file is readable by the package's config reader, which is the guarantee that actually matters.