Rust repo-local package ownership and condition taxonomy hardening

[jununfly]

This was generated by AI during triage.

What to build

Harden Rust core diagnostics for repo-local Cargo package ownership and condition-source taxonomy, without attempting active cfg evaluation or full Cargo resolution.

The implementation should keep package/crate ownership as diagnostic and guard input only. It should classify condition sources such as feature-gated, target-gated, test-only, and cfg_attr-affected Rust source so later graph writes can fail closed with precise reasons.

Acceptance criteria

• Rust result JSON/profile diagnostics expose or harden repo-local package ownership and crate-root ownership counts for indexed .rs files.
• Condition-source taxonomy distinguishes feature-gated, target-gated, test-only, and cfg_attr-affected source when detectable from parsed source.
• The implementation does not evaluate active cfg, feature unification, target triples, Cargo resolver v1/v2, or external dependency source.
• Existing Cargo workspace and Rust macro/cfg diagnostics remain backward-compatible unless the baseline issue explicitly justifies a taxonomy rename.
• Targeted Rust core tests pass.

Blocked by

• Rust Cargo/cfg diagnostics baseline fixture #602

[jununfly]

This was generated by AI during triage.

Closing as implemented. Rust core now exposes rustCargoConditionSourceCounts and hardens repo-local package/crate ownership plus condition-source taxonomy without active cfg evaluation or full Cargo resolution.

Verification: cargo test -p zcodegraph-core rust_core_ -- --nocapture; cargo test -p zcodegraph-core.