[astro]

Closes #115

[dajiaohuang]

One CLI edge worth clarifying before relying on this as a general output mode: FILE_PATHS accepts multiple files/directories (and defaults to .), but this branch prints only each changed file's rewritten contents to stdout, concatenated without a filename or delimiter; unchanged files emit nothing. With multiple inputs, a consumer cannot map the output back to its source file. If the intended dprint integration always invokes deadnix once per file, documenting/enforcing that single-file contract would address this; otherwise the stdout format needs to preserve per-file boundaries. Also, --stdout without --edit currently silently has no effect, although its help text promises output; could the CLI either reject that combination or make the dependency explicit in help?