fixture3

Verification

Do not add Rust unit tests, integration tests, doc tests, or inline #[test] functions.
Do not add a tests/ directory.
Do not use cargo test as project verification.
Use fixture3 behavior suites as the verification model.
Use per-workspace cargo check, cargo clippy, cargo fmt --check, and g3rs validate --rules-only for compile and static checks.
As soon as the CLI can run one command, it must verify its own fixture suite through fixture3 check.

Keep guardrail3-rs.toml inside each Rust workspace root.
Keep [checks] test = false.
Treat any new G3RS failure as a code or architecture failure unless the plan explicitly changes the guardrail.