Polish the integrated Rust CLI so the branch ships like a usable deliverable instead of a scaffold. This adds explicit version handling, expands the built-in help surface with environment and workflow guidance, and replaces the placeholder rust README with practical build, test, prompt, REPL, and resume instructions. It also ignores OMX and agent scratch directories so local orchestration state stays out of the shipped branch.\n\nConstraint: Must keep the existing workspace shape and avoid adding new dependencies\nConstraint: Must not commit .omx or other local orchestration artifacts\nRejected: Introduce clap-based top-level parsing for the main binary | larger refactor than needed for release-readiness\nRejected: Leave help and version behavior implicit | too rough for a clone-and-use deliverable\nConfidence: high\nScope-risk: narrow\nReversibility: clean\nDirective: Keep README examples and --help output aligned whenever CLI commands or env vars change\nTested: cargo fmt --all; cargo build --release -p rusty-claude-cli; cargo test --workspace --exclude compat-harness; cargo run -p rusty-claude-cli -- --help; cargo run -p rusty-claude-cli -- --version\nNot-tested: Live Anthropic API prompt/REPL execution without credentials in this session
