Add GitHub Actions CI for formatting, tests, and linting

[wan0net]

Summary
This repository currently has no GitHub Actions workflows.

Evidence

• No .github/workflows/*.yml or .yaml files are present in the repo
• The crate already has unit tests in source modules and is a standard Cargo library

Why this matters
Basic CI would catch common regressions early:

• broken tests
• formatting drift
• lint issues
• documentation/example drift if doctests or README checks are added later

Suggested scope

• Add a workflow that runs on push and pull request
• Run:
  • cargo fmt --check
  • cargo test
  • cargo clippy --all-targets -- -D warnings
• Optionally add a docs/doctest step once the README example is corrected

Acceptance criteria

• PRs and pushes trigger a Rust CI workflow
• Formatting, tests, and clippy all run automatically
• CI status is visible in GitHub and blocks obviously broken changes

[wan0net]

Hermes automation update

• Queued [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_015efc42) for ford-prefect.
• Started [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_015efc42) with ford-prefect.
• Blocked [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_015efc42): Need GitHub write access to finish: this worker can read Add GitHub Actions CI for formatting, tests, and linting #3 but cannot update the issue body/comment or add the ready label because gh is unauthenticated and no GitHub token is available in the e...
• Note from ford-prefect on [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_015efc42): Prepared execution-ready spec, but I cannot write it back to GitHub from this worker because the environment has no GitHub credentials: gh issue view failed with gh auth login required, GH_TOKEN/GITHUB_TOKEN are unset, and ~/.git-credentials has no github.com entry. ...

[wan0net]

Hermes automation update

• Archived [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_015efc42) on the Kanban board.
• Queued [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_ab9cf368) for ford-prefect.
• Started [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_ab9cf368) with ford-prefect.

[wan0net]

Hermes automation update

• Started [Add GitHub Actions CI for formatting, tests, and linting #3] Specify: Add GitHub Actions CI for formatting, tests, and linting (t_ab9cf368) with ford-prefect.