Add cross-project PTO conformance impact workflow

[zhoubot]

Summary

• add exact read-only graph dependencies and cross-project conforms-to / expected-absent tracks validation
• preserve stable PTO ASL instruction identities and index semantic facets
• add deterministic PTO release impact analysis plus ndf impact pto-release
• document compatibility rules and validate 10,000-node consumer impact scale

Compatibility

Format 0.2, canonical IR 0.1, JSON envelope schema 0.1, SQLite schema v1, and the plugin API version remain unchanged.

Verification

• cargo fmt --all --check
• cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
• cargo test --workspace --all-features --locked
• NDF_RUN_SCALE_TESTS=1 cargo test -p ndf-compiler --test scale --release -- --nocapture

Scale evidence on the release-test host: 100,000 nodes / 1,000,000 edges built twice in about 1.46-1.48 seconds; 10,000-consumer impact ran twice in about 0.034 seconds with identical JSON.