Summary

• add Rust tech-stack detection and select a dedicated Rust issue-implementation skill for traditional Rust repositories
• add bundled Rust implementation skill assets plus Rust-specific prompt guidance covering Cargo workflows, safety, and dependency checks
• cover Rust detection, skill selection, and prompt/security guidance with regression tests

Validation

• go test ./internal/repo ./internal/skill
• go test ./...
• go vet ./...
• govulncheck not installed in this environment

Benefits

• gives Rust repositories repo-aware implementation guidance without changing existing monorepo selection behavior
• keeps Rust validation expectations explicit for cargo fmt, cargo test, cargo clippy, and dependency/security tooling when available

Closes #358