Complete toolchain implementation and add comprehensive testing

[avrabe]

Description

This issue tracks the work needed to complete the rules_rocq_rust implementation.

Remaining Work

1. Toolchain Implementation

   • Complete binary download and verification
   • Add platform-specific toolchain support
   • Implement hermetic toolchain management (fix: download Rust nightly hermetically for coq_of_rust build #25 — hermetic Rust nightly download)

2. coq-of-rust Integration

   • Finish OCaml toolchain implementation (via nixpkgs)
   • Enable coq-of-rust extensions
   • Add Rust to Coq translation support

3. Testing Infrastructure

   • Set up CI/CD pipeline (macOS + Linux)
   • Add proof verification tests (point_proofs_test, advanced_verified_test)
   • Add integration tests for rule loading and toolchain setup
   • Add mock toolchain for testing without Nix

4. Documentation

   • Create advanced examples (advanced.rs with generics, traits, lifetimes)
   • Complete API reference
   • Add contribution guide

Acceptance Criteria

• All toolchain features working
• coq-of-rust integration complete
• CI/CD pipeline set up and passing
• Comprehensive test coverage
• Complete documentation

Related

• Part of rules_rocq_rust roadmap
• coq_of_rust build fails: libLLVM-19-rust-1.85.0-nightly not found during repository fetch #24 fixed hermetic Rust sysroot (fix: download Rust nightly hermetically for coq_of_rust build #25)

Priority

Medium — Core functionality is complete, remaining work is hardening and docs