Add a focused GitHub Actions workflow for pull requests into main plus
manual dispatch. The workflow checks workspace formatting and runs the
rusty-claude-cli crate tests so we get a real signal on the active Rust
surface without widening scope into a full matrix.
Because the workspace was not rustfmt-clean, include the formatting-only
updates needed for the new fmt gate to pass immediately.
Constraint: Keep scope to a fast, low-noise Rust PR gate
Constraint: CI should validate formatting and rusty-claude-cli without expanding to full workspace coverage
Rejected: Full workspace test or clippy matrix | too broad for the one-hour shipping window
Rejected: Add fmt CI without reformatting the workspace | the new gate would fail on arrival
Confidence: high
Scope-risk: narrow
Directive: Keep this workflow focused unless release requirements justify broader coverage
Tested: cargo fmt --all -- --check
Tested: cargo test -p rusty-claude-cli
Tested: YAML parse of .github/workflows/rust-ci.yml via python3 + PyYAML
Not-tested: End-to-end execution on GitHub-hosted runners
