add Rust SDK crate 0.0.1

[waterbang]

Summary

• add the official blocking Rust client for CCCC Daemon IPC v1
• support Unix Socket/TCP discovery, generic JSON calls, structured errors, compatibility probes, and common group/chat/inbox/context helpers
• add Rust docs, live compatibility example, release guidance, and CI

Validation

• cargo fmt --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-targets (5 passed)
• rustdoc with warnings denied
• cargo package --locked
• cargo publish --dry-run --registry crates-io
• live connection to Rust CCCC 0.4.33