Pre-submission checks

• I am not reporting a bug (crash, false positive/negative, etc). These must be filed via the bug report template.
• I have looked through both the open and closed issues for a duplicate request.

What's the problem this feature will solve?

Running zizmor without any arguments currently produces a clap required argument error.

In practice, I would assume that the most common local invocations are zizmor . from either a repository root, root/.github/, or root/.github/workflows. This is a small paper cut that adds friction to the most common use case, in particular for new users.

Since zizmor is a single-purpose command (i.e. it has no subcommands), there's no ambiguity about what the user wants when they type zizmor. Users who want to learn more will type zizmor --help.

Describe the solution you'd like

Check the current working directory by default when the inputs argument is omitted. In other words, change inputs from #[arg(required = true)] to #[arg(default_value = ".")] so that bare zizmor behaves identically to zizmor ..

Additional context

This proposal would behave similarly to several existing tools and linters (e.g., actionlint, flake8, ruff check/format), which default to the current working directory when no input is explicitly provided.