feat: Cargo Package Management Integration [bounty #100]

[jing11223344]

Summary

Implement Cargo Package Management Integration for Rust language support in Lux, enabling seamless dependency management and build system integration. This completes the "Rust Integration (Coming Soon)" section in the language support documentation.

Changes

New Files

• lux/lib/lux/rust.ex - Main Rust module with: eval/2, create_project/1, add_dependency/2, build/1, test/1, read_cargo_metadata/1, available?/0, version/0, cache/clear
• lux/priv/rust/Cargo.toml - Default Cargo.toml template
• lux/priv/rust/src/lib.rs - Rust runtime utilities (version comparison, dependency resolution)
• lux/guides/language_support/rust.livemd - Comprehensive usage guide with examples

Modified Files

• lux/mix.exs - Added Rust priv files to package config, added Rust guide to docs

Test Files

• lux/test/unit/lux/rust_test.exs - Unit tests for core functionality

Acceptance Criteria

• Cargo.toml management (generation and parsing)
• Dependency resolution system
• Build pipeline integration (cargo build, cargo test)
• Version management
• Package caching mechanism
• Documentation with examples
• Unit tests

/bounty $300

[jing11223344]

Hi maintainers! This PR adds Cargo package management integration as specified in the bounty requirements. It's been open for a while and passes CI. Could you take a look when you have a moment? Happy to make any adjustments needed. 🙏