Add comprehensive plan for Rust client implementation including:
- TCP transport (v1.1) support
- RNS transport (v1.2) support via FFI with microReticulum
- Architecture with transport abstraction
- Module structure and dependencies
- CLI command design
- Testing strategy
- Implementation priority
Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>
