Rust Cargo/cfg diagnostics fixture smoke and closeout evidence

[jununfly]

This was generated by AI during triage.

What to build

Close out the Cargo/cfg diagnostics hardening v1 implementation with deterministic fixture evidence and a mini-redis real-repo smoke, then record the result in a durable benchmark/decision artifact.

This slice should verify that diagnostics improved while graph writes stayed conservative and Rust indexing still succeeds on the real Rust corpus.

Acceptance criteria

• Deterministic fixture tests cover Cargo package ownership, crate-root ownership, cfg/feature condition-source taxonomy, and generated/build-script no-go taxonomy.
• A mini-redis smoke run records Rust core result JSON/profile evidence for Cargo/cfg diagnostics.
• The closeout artifact records whether the next safe slice is ready, no-go, or needs-oracle/research.
• The roadmap is updated through the roadmap CLI and rendered after the closeout decision.
• No agent A/B or performance gate is added for this semantic diagnostics slice.
• Targeted Rust core tests and git diff --check pass.

Blocked by

• Rust conditional semantic edge suppression diagnostics #604

[jununfly]

This was generated by AI during triage.

Closing with closeout evidence recorded in docs/benchmarks/2026-06-27-rust-cargo-cfg-diagnostics-hardening-evidence.md. mini-redis smoke passed and roadmap was updated through the roadmap CLI.

Verification: target/debug/zcodegraph-core index --project-path /private/tmp/codegraph-corpus/mini-redis --index-path /private/tmp/codegraph-corpus/mini-redis/.zcodegraph/zcodegraph.db --force; cargo test -p zcodegraph-core; git diff --check.