Align goark/today repository layout with spiegel-im-spiegel/linkcard structure

[Copilot]

today was a minimal repository and did not follow the same project/release/CI scaffolding pattern as linkcard. This change brings today to the same structural baseline while keeping project-specific names and behavior.

• Project scaffolding parity

  • Added top-level config files to match the reference layout: .editorconfig, .gitattributes, .goreleaser.yml, Taskfile.yml, dot-config.toml.
  • Extended .gitignore with build/task artifact paths used by the same workflow style (bin/, dist/, .task/).

• GitHub automation structure

  • Added .github/workflows/ci.yml, build.yml, and codeql.yml with the same workflow composition pattern as linkcard.
  • Added .github/copilot-instructions.md in the same placement/style.

• Go module and internal package layout

  • Introduced Go module root and executable entrypoint (go.mod, main.go).
  • Added internal package split mirroring the reference architecture style:
    • internal/config (CLI option parsing),
    • internal/ecode (exit codes),
    • internal/facade (execution flow),
    • internal/today (date rendering).

• Minimal behavior implementation + focused tests

  • Implemented default output as today’s date string and --version handling.
  • Added targeted unit tests for date formatting and config parsing.

func main() {
	os.Exit(facade.Execute(
		os.Stdin,
		os.Stdout,
		os.Stderr,
		Version,
		os.Args[1:],
	))
}

Original prompt

https://github.com/spiegel-im-spiegel/linkcard リポジトリと同様の構成にして下さい

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