fix(opy): converge semantic failure frontiers

[e54-bot]

Summary

• Move invalid range binders and four-dimensional indexed assignments to the source semantic failure frontier.
• Preserve stable source-attributed diagnostics and update compiler/differential/conformance expectations.
• Reclassify canonical-WIR residuals to the lowering boundary and remove obsolete integration-only assertions.

Validation

• cargo fmt --all -- --check
• cargo clippy --locked --workspace --all-targets --all-features -- -D warnings
• cargo test --locked --workspace --all-targets --all-features
• python3 -m unittest discover -s compatibility/tests
• Offline conformance: 63 fixtures; Converge semantic resolution and catalog-backed source conformance exposed by #158 #162 probes match.
• Independent ablation confirmed the semantic regression fails when the new guards are removed.

Fixes #162