Rust file package and crate-root ownership diagnostics

[jununfly]

This was generated by AI during triage.

What to build

Add diagnostics that classify Rust source files by Cargo package ownership and crate-root context where that can be determined safely. This should make package and crate-root boundaries visible to profile/evidence output without changing same-crate graph behavior or writing cross-package edges.

Plan: docs/plans/2026-06-27-rust-language-indexing-plan-4-cargo-workspace-package-frontier.md

Roadmap node: 1-4-4-2

Acceptance criteria

• .rs files in a package are classified by package ownership when deterministic.
• Crate roots are classified as lib/bin roots where deterministic.
• Non-root module files inherit enough ownership context for diagnostics.
• Ambiguous or out-of-workspace files are classified as unresolved/deferred rather than guessed.
• Existing Rust graph output is unchanged except for diagnostics/profile data.
• No cross-package graph edges are written by this slice.

Blocked by

• Rust Cargo.toml package and workspace metadata taxonomy #578

[jununfly]

This was generated by AI during triage.

Closing as implemented. Rust-owned indexing now classifies Rust files by deterministic Cargo package ownership and crate-root context in diagnostics/profile data, without changing same-crate graph behavior or writing cross-package edges.

Evidence: docs/benchmarks/2026-06-27-rust-language-indexing-plan-4-evidence.md

Verification: cargo test --package zcodegraph-core, npm run build.